XYit
The Image Digitiser
from Geomatix
Introduction
Getting Started
Advanced Options
Menus
Data Entry Panels / Dialogue Boxes
and Windows
Technical
Introduction
With XYit you can
capture the positions of lines and points within images.
The images may be of graphs, maps,
diagrams or pictures With XYit you can export the data points in
their original XY co-ordinates into a word processor or a spreadsheet
for analysis. The image may have been produced by scanning, it may be from the
internet, or it may be in any other application program which you
can run on your PC. It can even be distorted, skewed, squashed, rotated or
stretched. So with XYit you can even get accurate data from plans
which are no longer square and from digital photographs which have optical
distortions. You can also reverse the above process and display your own points
onto images in the correct registration. And whether your axes are logarithmic,
or are Mercator co-ordinates you can still retrieve your data! The horizontal
axis can even be a Windows date – which is useful for analysing graphs of a
variable against date.
Application
XYit, formerly known as i-extractor,
has been used by staff at research centres and universities worldwide for
analysing financial graphs, diagrams, maps, nautical charts, and scientific
plots.
Applications have included:-
·
financial
graphs e.g. stock market prices
·
Nautical
Mercator charts - cable and pipeline survey maps
·
grid
maps - UK Ordnance Survey
·
building
plans
·
scientific
graphs
·
hydrography
- graphs of tidal height.
·
infra-red
spectra
·
chromatograms
e.g. gene identification.
When you use XYit you
trace over the things in the image which you want to extract. This is called
digitising. You can do this manually or automatically. More on Digitising
If you are new to XYit
you will probably want to look at Getting Started
Advanced
Advanced
OptionsADVANCED
Changing
Calibration or Scale
Merging
Data from Different Maps
Placing
Points or Lines onto an Image
File|New MapMENU_NEW
File|Load Image
File|Load Data
File|Save Data
File|Save Image
File|Exit
Edit|Copy Data
Edit|Copy Image
Edit|Paste Data
Edit|Paste Image
Edit|Delete All Points
Edit|Delete Current
Edit|Insert After
Edit|Insert Before
Edit|Reverse Order
Edit|Edit Current
Edit|Reload Image
Edit|Flip or Rotate
Edit|Grab Screen
View
View|Magnifier
View|Current Point
View|Distance / Area
View|Statisics
View|Data
Setup|Axis Type
Setup
Setup|Calibrate
Setup|Calibrate|By Frame
Setup|Calibrate|By Frame|Set Frame
Setup|Calibrate|By Frame|Enter
Corners
Setup|Calibrate|By Triangle
Setup|Display Settings
Tools
Tools|Digitise by Scanning
Tools|Digitise by Crawling
Tools|Remove Excess Points
Help|Find
Help|IndexMENU_HELP_INDEX
Help|Contents
Help|This Screen
Help|Technical Support
Help|Geomatix on the web
Help|LicenceMENU_LICENCE
Help|AboutMENU_HELP_ABOUT
Windows
Main ScreenDLG_MAIN
Load Data-Options
Digitise by Scanning
Digitise by Crawling
Setup Axis - Lables and Types
Magnifier
Current Point
Data ViewerDLG_DATA_VIEWER
Edit PointDLG_EDIT_POINT
Distance / Area
Enter Corners
Remove Excess Points
Flip or Rotate
Digitise by Crawling
Licencing
StatisticsDLG_STATISTICS
Display Settings
Triangle FixDLG_BY_TRIANGLE
Getting Started
Choose an image which you want to
digitise, to start load our example images, example1.gif, example2.gif
Use File|Load Image to load
an image in any of 20 image formats.
Try moving the image with the right
mouse button or the scroll bars. You can zoom using the + and - keys.
Try activating the magnifier with
the view magnify menu. If necessary, move the magnifier away from the main
screen.
The readout is presently in pixels.
After setting up the image it will read out in your real world units, i.e. the
actual values from your graph or map.
Try clicking on the image to create
some points
Now you should setup the image as
follows.
1. Set the type of axis to take account
of what kind of axis you want. Generally it is a linear number so you may be
able to skip this step. If you know that you want to use a date, a logarithmic
axis or Mercator co-ordinates see Setting Axis Type, and then come back here
2. Unless you are happy with a
readout in pixels you will need to calibrate your image.
To do this you simply enter some
known corners or some known points into the system. Next
Calibrating an
Image
XYit needs to know what the values are
at some places in the image. The process depends on the type of image you have.
Click here if it has a rectangular frame,
straight line axes, or at least two intersecting grid lines at opposite
corners. Examples are graphs, maps, nautical charts.
Click here if it has three known points, (one
of which can be an intersection of grid lines). An example may be a scanned
maps or plan on such a large scale that a grid frame does not appear.
Calibrating by Corners
Use these instructions if your
image has 2, 3 or 4 corners of a grid, frame or axis visible and you know the
values that these lines represent.
1. Click Setup|Calibrate|by
Frame
Click Set
Frame.
·
Use
the 2 Corners option if you know your image is perfectly aligned with
the screen display and has no distortion (e.g. a web generated graph). Select
the corners and proceed by clicking the corners of your image as instructed.
·
Use
the 3 Corners option if you know your image may be scaled incorrectly,
but the worst distortion that has occurred is that the axes in the original
image have become a parallelogram i.e. the axes are not at right angles. Select
the button which corresponds to the 3 corners you have, and proceed by clicking
the corners of your image as instructed.
·
Use
the 4 Corners option for the greatest accuracy. This will work even if
the axes form an irregular quadrilateral i.e. it is so distorted its not even a
parallelogram. For example a paper map may have been stretched before it was
scanned or it may be a digital photograph of a map and therefore contains
optical and perspective distortion. Proceed by clicking the 4 corners of your
image as instructed.
2. Go to the Setup|Mapping|by
Frame|Enter Corners menu and enter the real co-ordinates values of the
frame lines in real co-ordinates.
Next click OK.
Now you should check that the image
is setup correctly.Next
Calibrating by 3 Points
Use these instructions if you know
the position of three arbitrary points in the image and you know the values
which these points represent. For example you may have a nautical chart and
although you cannot see any parallels or meridians you do know the position of
a lighthouse and two buoys. Or you may have a graph and know three points on
the graph but you cannot see the axes on the image. We call the process of
calibrating XYit using three known points 'by triangle'
since the points form a calibration triangle.
Click Setup|Calibrate|by
Triangle
Click the 3 points of which you
know the co-ordinates. For the best results these should be quite near the edge
of the image, and they should be roughly equally spaced. They should definitely
NOT be in a straight line. Enter the x and y values into the boxes provided and
click OK.
Now you should check that the image
is setup correctly.Next
Checking Image
Setup
As a check you probably want to
know that you have now set up the image correctly.
To do this check first switch on
the cursor readout using the Window|Magnifier menu. You may find it
easier to drag this window to another part of the screen away from the main
form of XYit.
As you move the mouse cursor around
you will see the real values of your graph, map or plan, are shown in the
Magnifier Window. Notice that you can scroll or drag the image around or resize
the main window and the readout will still remain in the correct registration.
Check the calibration points or
lines which you have entered give the correct reading.
If you know some other points or
lines, check these readout correctly. If you have a problem you have probably
entered some values incorrectly, so go back to the enter corners or enter
triangle windows.
If all is OK you are now ready to
start digitising the lines and points in your image.
Digitising
If you have set up your image and checked
your image setup to your satisfaction, you are ready to start extracting
data from your image.
This process will create a set of
data points superimposed on the image to scale. You will be able to export the
true coordinates of these points to the clipboard for export.
One of the points is the selected
point and is shown in a different colour. You can change the selected point by
using the up / down arrow keys, the Page-Up / Page Down-keys, Home, and End
keys.
There are three ways to extract
data from (digitise) your image.
Manual Digitising.
Trace the line manually with the
mouse. more
Scanning
You can scans the image to look for
certain coloured pixels. more
Crawling
You can crawl along a coloured line, like an ant,
converting likely pixels into points. more
Manual Digitising
To manually digitise a feature of
an image, just click the mouse on the points in the image in order.
You can seethe points you have
digitised as real values in View | Data.
Other useful functions.
To change the line appearance
Use the Display menu to join or
un-join the points and to change their colour
To changing the selected point
Use the horizontal arrow keys to
move the select the point.
To insert new points within a line
Use the Points menu to set whether
you want to insert before or after the current point..
Editing Data Points
One of the points is the selected or current point and is
shown in a different colour - default red. Its co-ordinates and index are
displayed in the current point display window. It can be deleted or edited by
using the Edit menu.
You can navigate along the data points using the following
cursor keys.
Up Move
to previous point.
Left Move
to previous point
Down Move
to next point
Right Move
to previous point
Home Move
to beginning point
End Move
to last point
Page Up Move
towards the beginning by 10%
Page Down Move
towards the end by 10%
Saving and Loading
DIG Files
XYit saves your digitised points in
real world map co-ordinates in a dig file. The dig file also contains the
calibration reference frame or triangle of reference points.
Since the
dig file contains the reference points and the data in real world co-ordinates
it allows you to merge DIG files which you have made between maps of different
scales and it allows you to re-calibrating half way through a job.
Dig files
are plain ASCII so you can review the data in there, but be very careful not to
edit them or you may lose all your data. XYit can save your
digitised data to a file or to the clipboard.
When
saving data to a file, the first two lines of the data contains the calibration
points, and the remainder of the file contains the data points. If you want to
export your data e.g. to a word processor or a spreadsheet (e.g. Word/Excel) it
is better to use the clipboard|Save Data menu function and use the
Edit|Paste function in the destination program. With this method the
calibration information is not imported or exported as you almost certainly
won't need it.
Note that
on un-licensed copies you cannot save your data. Please purchase XYit
to save your data.
Advanced Options
Since XYit
saves your digitised points in real world map co-ordinates together with the
calibration points it allows you to re-calibrate, change scales, or merge data
from different maps half-way through a job.
1.
Changing Calibration or Scale
In Getting
Started we said that you should set-up your image calibration first. In fact
this is not strictly true, you can actually change calibration half way through
a job. For example, you can load an image, just start digitising and then apply
the frame set-up later. Or you could change a graph say from meters to feet
half-way through a job.
2.
Merging Data
You can
also merge data which you have got from different maps. For example, if you are
digitising a pipeline which goes across three different maps you can produce a
single file of alter course co-ordinates, providing you use the same datum and
mapping system for each map. If they are in a different system then you can use
our other package DatumPro to convert the dig file to the different datum or
grid system. DatumPro is also available from www.linden-software.com on-line.
Changing Calibration or Map Scale
If you
want to change the calibration which you have set up (Frame / Corners /
Triangle) or you have already digitised some points then there is no need to
delete the digitised points and start again, you can re-calibrate half-way
though.
Use this
option if :-
a. You
have digitised data but did not set up a Frame / Corners
b. You
want to change the scale but want the data points to appear in the same place
on the map.
Steps
1. Save
your data points in a DIG file using File|Save Data
2. Delete
all the points in memory with Points|Delete All
3. Load
the image again with File|Load Image
4.
Recalibrate the image by using either a for a grid the Setup|Calibrate|byFrame
and Set_Frame & Set Corners or for a triangle (3 un-related
calibration points) using the Setup|Calibrate|byTriangle.
5. Re-load
the original data with File|Load Data but use Option 2: Load
points with frame and region as currently displayed but preserve image
locations.
6. You can
now continue digitising as normal.
Your old
data and new data will be merged and saved with the new calibration.
Merging Data from Different Maps
You may
have a number of different files, say of a pipeline produced from different
maps. It is easy to use XYit to merge data between different
files. This is possible because XYit saves the digitised points
in real world co-ordinates - so it can readily merge the data which has been
stored from maps, even if they used different scales.
Steps.
1. Delete
any points which may be in memory with Points|Delete All
2. Click File|Load
New Map which tells XYit to use a blank image or you can load
a small-scale (large area) map to overview the merged data.
3. Click Setup|Calibrate
and click the byFrame (using Set_Frame together with Enter
Corners) or use the byTriangle options to calibrate the corners of
the blank map or the overview map
4. Re-load
the data with File|Load Data but use Option 3. Load points
onto current frame as real locations. Essentially this option tells XYit
to ignore the calibration in the file and to just to use the point data
directly.
5. You now
can merge the next data set. Use Points|Reverse Order if necessary to
reverse the order of the points in memory. Check they are in the required order
by using the Home and End keys. Of course it is easier if the points in all
files are digitised in the same direction (order).
6. Repeat
Step 3, 4 and 5 as required.
7. Click File|Save
to save the merged data.
You can
now continue digitising or saving. The old data and new data will be saved with
the new calibration.
Dig files
are plain ASCII so you can review the data in there, but be very careful not to
edit them or you may lose all your data.
Placing Data onto an Image
You may
also use XYit to place your vector co-ordinates onto a map or
graph. This is useful for creating maps of proposed activities or in
identifying points upon a pre-existing graph.
XYit needs
to read the data from the clipboard as tab delimited text in plain ASCII. The X
co-ordinate should be first, followed by the tab and then the Y co-ordinate.
Steps to Placing
Data
1. First
run XYit and load and calibrate your image as described in.
Getting Started
2. Now go
to your source software application and copy the data onto the clipboard. If
you are using a spreadsheet or a Table in Microsoft Word you can do this by
highlighting the columns containing the co-ordinate data. Then click Edit|Copy
or Ctrl C keys. This will copy the data to the clipboard.
3. Click Clipboard |Getdata and your data
will be displayed in the correct registration superimposed upon the image.
4. Use the
Display
options to change the thickness and colour of lines and points.
5.
To save the image Click the PrintScreen key. This will capture the image -
including the points – ready for export to a Word Processor, where you should
use the Ctrl V keys or Edit|Paste function provided.
Licence Window
XYit provides an evaluation period
during which time it is fully functioning. However, after this time has elapsed,
you will have to purchase XYit to save data.
When you
purchase XYit you will receive a licence code which you should enter into the
box provided. You will only have to enter the code once.
Buy now will activate your default browser
on our website.
Buy
Later takes you to
the evaluation version of this program.
Main Screen
The Main Screen is used for
digitising the image and for accessing the various menus.
|
Mouse Functions |
|
|
Right Click |
Digitise a point |
|
Left Click & Drag |
Move - pan image |
|
|
|
|
Keystrokes |
|
|
+ plus |
Zoom In |
|
- minus |
Zoom Out |
|
left arrow <= |
Select previous point |
|
right arrow => |
Select next point |
|
|
|
|
Menus |
|
|
File: |
Load, save data and images |
|
Edit: |
Access clipboard, manage data
points, change image |
|
View: |
Activate viewers, such as the
magnifier and data viewer |
|
Setup |
Functions to set up the axes and to calibrate the
image |
|
Tools |
Tools which automate digitising. |
|
Help |
Access this help file and
technical support |
Menu: File
The File menu options and
purpose are listed below.
·
New
Map: Load an image
for you to digitise manually or automatically.
·
Load
Image: Load xy
data which you have created from your image.
·
Load
Data: Load xy data
which you have previously saved.
·
Save
Data: Saves xy
data which you have previously saved.
·
Save
Image: Save the
image and the xy data in a graphics file format
·
Exit Exit from XYit.
Menu: File | New Map
New Map
Use this option to create a new
blank map. This is useful when merging data from different maps or sources, and
when you want to view your digitised data against a blank background.
Menu: File | Load Image
Load Image
Use this option to load a source image (graphic) into XYit.
XYit supports over 20 different formats and can easily handle graphics files
larger than 10 Mbytes. Loading an image file will delete all the current
digitised points, and you will be asked whether this is OK before proceeding.
Window: Load Data
Use this option to load previously
saved data. When data is saved by XYit it is stored so that its screen
coordinates and its xy positions can be retrieved. This makes it possible to
join xy data created between different digitising sessions, or even from maps
of different scales.
This versatility means there are 3
ways to load data.
1. Load points with frame and
region exactly as saved.
This is the most commonly used
option and is used for carrying on with digitising a map from where you left
off.
2. Load points with frame and
region as currently displayed but preserve image locations. Use this option if you are using
the same image as before, but have changed the scaling or re-defined the
corners since you last saved the file. This is useful if you started off say in
meters but have now changed to feet, or if you have changed from grid
co-ordinates to latitude and longitude on the same map. Or you can use this
option if you did not define the corners and scale before when you were
digitising, but now you have calibrated the map by entering the corners.
3. Load points onto current frame
as real locations.
Use this for joining up data which
has been sourced from different maps. The data does not have to have been
digitised in the same scale on each map, but rather the data can be joined from
maps of different scales.
Menu: File | Save Data
Save Data
Use this option to save data points which you have
digitised. The data is saved in plain ASCII, with a tab delimiter between data
pairs and is suitable for input to Microsoft Excel etc. The file contains
headers which include information regarding the calibration and corner
positions. This data can be ignored when importing co-ordinates into other
applications.
See also Edit | Copy Data
Menu: File | Save Image
Save Image
This option saves an image to a file, as a
windows-bmp, jpg or gif. The data points which you have digitised will also be
saved in this image. This enables you to create images for reports which
include lines or points which you have digitised or imported.
Menu: File | Exit
File|Exit
Use this option to quit. If you
have changed the display settings you will be prompted to save them. Notice
that the display settings relate to things like the colour and size of lines
and points and not to the digitised data coordinates themselves.
See also Saving Data. Are you
prompted when quitting to save the current points
To save your digitised data you
should Your digitised must be saved separately using the previous option.
Menu: Edit
The edit menu is used to interact
with the clipboard, to edit the data points, and for simple image functions.
The windows clipboard is an area of memory which is common to all applications
and can be used to transfer data and images between applications.
Menu: Edit | Copy Data
Copy Data
This option copies the digitised data points within
XYit to the clipboard. Unlike when saving co-ordinate data to a file, the data
is saved without the calibration and other header information which is normally
included when saving to a file. If the image has not been calibrated, the xy
values which are copied are in pixel co-ordinates. Having copied the data to
the clipboard, it can be imported into another application by using the
Edit|Paste function e.g. within your spreadsheet or word processor. To import
the data into a table in Microsoft Word, first highlight the table (or rows and
columns) where you want the data to be entered, and then use Edit|Paste
The clipboard data format is ASCII
text, with a tab delimiter between data pairs, and a carriage return linefeed
between successive records. This data format is suitable for input to Microsoft
Excel and Lotus 123.
Menu: Edit | Copy Image
Copy Image
Use this option to copy the loaded
images within XYit to the clipboard. The image which is copied will include the
data points and lines which you have digitised. Of course if you do not want
these points and lines on the image you can delete them first. This image is in
bmp format and can be imported into other documents e.g. Microsoft Word using
the Edit|Paste function from that application.
Menu: Edit | Paste Data
Paste Data
Use this option to import data
points into XYit. from the clipboard. This is a way of putting data points onto
your image in the correct registration.
The data points should appear in
the clipboard as text of the form
<x1value>TAB<y1value>
<x2value>TAB<y2value>
…….
You can check that they do, in
fact, look like this by using the paste option to view them in a text editor.
The xy values should be in real
world co-ordinates as you have defined them in your image set-up. If the image
has not been set up, the imported xy values will be interpreted as pixel
values.
The data points are appended to the
data points already within XYit. If you want to see the imported points alone
you should delete all of the current points before using this command. However,
in some situations you may want to append the external points to the internal
ones.
Under normal situations this is all
you need to know. However more details of the format used by XYit is in Technical
Clipboard Data Format section
Menu: Edit | Paste Image
Paste Image
This option gets an image from the clipboard and puts it
into XYit. It is provided as an alternative route to File|Load Image. Like Load
Image clicking Edit | Paste will delete all the current digitised points within
XYit, and you will be asked whether this is OK before proceeding.
If no image is
available within the clipboard in the correct format, the option is disabled
and greyed out.
Menu Edit | Delete All Points
This is the start of the section of
the Edit menu containing options which enable you to manage the data points.
Delete All Points
Click this option to delete all the
current points. You are NOT prompted before proceeding so use this option with
care.
Menu Edit | Delete Current
Delete Current
Click this option to delete the
currently selected point - normally shown in red unless this colour has been
changed in the Setup|Display Settings window. You are NOT prompted before
proceeding so use this option with care.
Menu Edit | Insert Before , Insert After
Insert After, Insert Before
XYit either uses Insert After or
Insert Before as the insertion mode. Insert After means that subsequently
entered points will be inserted immediately after the currently selected point,
whereas Insert Before causes points to be inserted before the current point.
These options are useful for filling in sections which may have been missed.
Take the screenshot above as an example. The point numbers are increasing from
the bottom to the top of the line. So setting the Insert Mode to Insert After
makes it easy to fill in the missing section as shown below.
Menu Edit | Reverse Order
Reverse Order
Click this option to reverse the
order of the points, this can be useful when merging different data sets, or
where line objects have been digitised from opposite ends.
Window: Edit Point
The Edit Point window enables you
to enter the x and y values of a point as text.
Menu Edit | Reload
Image
This is the start of menu section relating to the display
the image on the XYit.
Reload Image
This option reloads the screen image from the file and
allows you to effectively start over again.
The image calibration is set by default to readout pixels.
The image should be re-calibrated if this is not appropriate.
Window Flip or Rotate
The Flip or Rotate Dialogue enables you to rotate or mirror
the image.
The image should be re-calibrated if this is not
appropriate. The image calibration is set by default to readout pixels after
rotation. Rotating the image will also delete all the digitised points
Menu Edit | Grab Screen
Grab Screen
Use this option to grab the underlying screen image. This
may be from another application such as graphics package or web-browser. In
operation XYit minimises itself for one second, it copies the
screen image into its main window, and finally it restores itself.
The image calibration is set by default to readout pixels.
The image can be re-calibrated if this is not appropriate.
Menu: View
This menu controls the display of subsidiary windows which provide
additional information. These subsidiary windows can be left on even when
digitising, although in some cases this may slow down the operation somewhat.
You may want to move these subsidiary window around so that you get a clear
view of both the main window and the subsidiary one(s) if displayed.
Window:
Magnifier
The magnifier is used to provide an enlarged view of the image in the
neighbourhood of the cursor especially when digitising a complex image as shown
above.
Note that sometimes the main screen
may hide or be on top of the magnifier window, since it necessarily has the
focus for digitising operations. You can place it back on top of the main
screen by using the desktop taskbar. However, we recommended that you move the
magnifier away from the main screen, unlike in the above screenshot, to avoid
this difficulty.
As well as providing a magnified
image, the magnifier gives a continuous readout of the cursor position in real
co-ordinates. It can be used for checking the image calibration during setup.
Window:
Current Point
Used to
display the currently selected point as text.
The x and y
labels are derived from the axis setup page. if the x axis has been set to type
"date" then the date corresponding to that point will be displayed
here
Window:
Area / Distance
Used to
display the line length and polygon area in real world units. The area of an
unclosed line is that of the polygon which would be obtained by joining up the
last and first points of the line. This can be useful for measuring the length
or area of objects within an image such as field plot areas, or road lengths.
Window: | Statistics
Used to continuously display the mean, maximum, minimum and standard
deviation.
This can be useful when statistical data is digitised.
Window:
Data View
The data
viewer continuously provides a text listing of the data point values as text.
You can also
change the currently selected point by clicking the displayed text data box.
Menu:
Setup
The menus
under this group are used for setting up an image, or for setting up the
display.
Axis Type enables you to set the type of axis:
linear, logarithmic, date or Mercator.
and the Calibrate
menus affect data are saved within the data points file when you save your
data.
The Setup|Display Settings Window enables you to
set up the cursor, and to the change colours, line widths and tool tip text
etc.
are saved to
a configuration file, so that the next time XYit starts up, it uses the same
display settings.
Window: Setup Axis
This form is used to set the type
of x and y axis, and also to enter the text labels for each axis. You can set
the x axis to number, date logarithm or Mercator, while the y axis can be
number, date logarithm or Mercator.
Use
Numbers
for linear graphs and grid maps of uniform projection.
Logarithm
for the respective axis on logarithmic graphs
Date for
graphs against time e.g. share equity prices.
Mercator
is used for nautical charts and maps in Mercator projection.
Menu:
Setup|Calibrate
There are two main ways of setting up your image.
The "Calibrate" menus leads to two options.
When setting up you can either use
the By Frame or ByTriangle. The ByFrame option is suitable for either graphs
with axes, maps with gridlines, or nautical charts with meridians &
parallels. If your maps or graphs does not contain any grid lines or axes you
should calibrate your image with the ByTriangle option which uses 3 known
points. The byFrame and ByTriangle options are described in more detail under
the menu options.
Menu: Setup|Calibrate|ByFrame
Use the ByFrame option if your
image is:-
a graph with
axes,
a map with
intersecting gridlines,
or a
nautical chart with intersecting meridians & parallels.
If you do not have at least 2
opposite corners you should see the ByTriangle option. When using the ByFrame
option you can enter up to 4 corners. By corners we mean:-
in the case of graphs "intersections
between lines which are parallel to the x and y axes",
for grid based maps "
intersections of grid lines",
for Mercator charts we mean "intersections
between meridians & parallels".
To calibrate you must enter and complete both
submenus, Set Frame and Enter Corners.
1. Set Frame activates the Set
Frame Window
where you can click on the corners so the system knows where they are. You can
use 2, 3 or 4 known corners.
2. Enter Corners activates the Enter
Corners Window
where you should enter the "real values" of the corners.
Window: Set Frame
XYit needs to knows where the
corners are on the image, so you now need to click the corners within your map
which you have chosen. Clicking the appropriate button here starts this
process.
·
Use
the 2 Corners option if you know your image is perfectly aligned with
the screen display and has no distortion such as a web generated graph or a map
from an electronic charting system.
·
Use
the 3 Corners option if you know your image may be scaled incorrectly,
but the worst distortion that has occurred is that your original rectangular
map frame or plan is now a parallelogram. You can also use this option if your
axes were never at right angles in the first place.
·
Use
the 4 Corners option for the greatest accuracy. This will work even if
the image is so distorted that its not even a parallelogram. For example, a
paper map which may have been stretched before it was scanned or a digital
photo of a map containing optical and other distortions would require the 4
corner calibration.
When you click the button the mouse
cursor will change to a large arrow. Place, the arrow tip in the appropriate
corner and click as shown below. Note that for clarity the
Repeat the process for the number
of corners you have selected. you must click the mouse in the order shown. You
should have no problem in remembering which corner to select next since once
you click, the mouse pointer changes to indicate the next corner.
Window: Enter Corners
Enter here the values of the
corners. Whether you have chosen to use 2 , 3 or 4 corners (intersection
points) there are only 4 values to enter because the corners are intersections
between horizontal and vertical lines. So it comes down to entering the values
for the left line, the right line, the top line, and the bottom line. The
values for the left and right lines can also be dates, provided the axis type
has been set to date. The way in which the axis type affects how the values are
interpreted is shown in the table below.
|
|
Representation |
Example |
|
X |
|
|
|
Number |
Floating point |
99.9 |
|
Date |
Windows short, medium or long
date |
11 November 2005 |
|
Log |
Floating point |
10000 |
|
Mercator |
Decimal Degrees +ve East -ve West |
99.9 |
|
|
|
|
|
Y |
|
|
|
Number |
Floating point |
99.9 |
|
Log |
Floating point |
99.9 |
|
Mercator |
Decimal Degrees +ve North -ve
South |
99.9 |
Menu: Setup|Calibrate|By Triangle
Use this option if you know of
three arbitrary points in the image and you know the positions which these
points represent.
For example, the image above is a
simple map of the English Channel between the UK and France. If you know the
positions of three points on the map then you can use these points to calibrate
it.
Click this option to display the Calibrate
ByTriangle Window
Window: Calibrate By Triangle
Use this option if you know of
three arbitrary points in the image and you know the positions which these
points represent.
For example, the image above is a
simple map of the English Channel. If you know the positions of three points on
the map then you can use this option to calibrate it.
Click the Point 1 button and click
the first point in the image. Continue until all 3 points are entered. For the
greatest accuracy these should be quite near the edge of the image, and they
should very roughly form an equal sided triangle. They should definitely NOT be
in a straight line.
Enter the x and y values into the 3
boxes provided and click OK.
You can then use the Magnifier
Readout to continuously provide your mouse position in real co-ordinates. Note
that, in the same way as the Enter Corners Dialogue, you can enter a Date as an
x co-ordinate for example when digitising historical graphs. When using the
Mercator option, the x and y values should be in decimal degrees.
Window:
Display Settings
Use this window to change the general appearance of the display.
Points:
Size Sets the size of the points in
appearance
Current Click this coloured square to
change the colour of the currently selected point.
Other
Points: Click this coloured square to
change the colour of the non-selected points.
Lines:
Width: Sets the
width of the line in pixels.
Style: Sets the
style of the drawn line to a number of different dot and dash sequences or to
continuous or transparent.
Line Colour:
Click this coloured square to change the colour of
the line.
Colour
Management
Display
Cursor as Cross: Replaces the normal mouse cursor with a small cross.
Display
Cross Hairs. Display cursor cross hairs (i.e. xy lines to the
edge of the image) in addition to the mouse cursor.
Cross
Hair Colour. Click this coloured square to change the colour of
the cross hairs
Tooltip
text: Click to enable or disable tool tip text. Once you
know how to operate XYit you may find the Tooltip text gets in the way.
Menu:
Tools
These Tools are mainly used for automatically digitise lines within an
image.
Digitise by Scanning scans the pixels within an image in a raster pattern, searching for
certain pixels colours. Use this option when the line is single valued for any
given x or y (that is, it does not loop around) and when the colour of the line
in which you are interested does not appear anywhere else on the image.
Otherwise use the Digitise by Crawling option
Digitise by Crawling begins a robot ant-like search, following adjacent pixels of certain
colours. In this way lines within the image are followed and digitised. Use
this option when the line is narrow, clear and distinct.
Remove Excess Points removes points from a line, subject to certain conditions. This can be
used after using either of the previous tools in order to reduce the number of
points to a manageable quantity. The error induced is minimal and can be
reduced to one pixel.
Window:
Tools|Digitise by Scanning
This tool
converts points and lines automatically, by identifying pixels of certain
colours within the image. You tell XYit where to start scanning, what colour
you want to be interpreted as a point, where to start the scan, and what
direction you want to scan. The colour does not have to be an exact match since
you can specify a tolerance colour range figure.
Set Initial Pixel
for Colour and Starting Point
This is
normally the first button to use. Click this button to identify the search
colour and the starting point of the scan. You can use the Magnifier to help
you to identify the correct pixel.
Set RGB or CMYK
Tolerances
Change to RGB or
CMYK
Changes
the colour system between RGB and CMYK.
You can
select the colour system used for the search. RGB may be better for images
which are not scanned or have a perfectly black background which were bmp or
gif images, while CMYK should be used for scanned or jpg images.
Colour Range +/-
Enter the
tolerance figure for each colour. RGB colours are 0 to 255, whilst CMYK are 0
to 100. A typical figure may be 5 or 10. For scanned images, or images poor
poor quality use a higher tolerance figure for the colour range.
At Each Value
Select First or Last
This
checkbox sets whether the first or last pixel is chosen on each row or column
which is scanned.
Limit
Search to Frame or Triangle
When set
the search area is limited as indicated – when not set the whole picture is
used.
Set Direction and
Go
Clicking
these zig-zag buttons starts a scan. which will scan horizontally or vertically
across the selected region. A progress indicator will inform you how quickly
the process is occurring.
Click Close
to finish the process.
Cancel
Closes the
window and deletes all of the points which have been created.
OK
Close the
window with all of the points remaining.
The points
are drawn as data points on top of your image. They have been converted to the
original co-ordinates and you can edit them in exactly the same way as with
manual digitising.
Menu: Tools|Digitise by Crawling
The line crawling digitiser can be
used to extract line data from an image automatically. Essentially it crawls
along a line looking for pixels of the same colour. It converts lines of the
same colour pixels into data points. XYit continues along a line
until all the line has been followed.
Steps
Set Crawl Starting Pixel. You will see its colour and screen
co-ordinates displayed within the panel. You can use the Magnifier to help you
if you want.
Set RGB / CMYK
Tolerances
Change to RGB /
CMYK
Changes
the colour system between RGB and CMYK.
You can
select the colour system used for the search. RGB may be better for images
which are not scanned or have a perfectly black background using bmp or gif
images, while CMYK should be used for scanned or jpg images.
Colour Range +/-
Enter the
tolerance figure for each colour. RGB colours are 0 to 255, whilst CMYK are 0
to 100. A typical figure may be 5 or 10. For scanned images, or images poor
poor quality use a higher tolerance figure for the colour range.
Initial Crawl Arrow Buttons
Click the button which bests
represents the initial direction required for the crawl.
Clear Points
This option will clear any points
which have already been digitised.
Stop
Stops the current crawl.
Close
Closes the window leaving the
points remaining on the main screen.
Note: In the case of a wide line XYit
may double back along the uncovered pixels of the line. The second set of
points can be removed by deleting the appropriate points manually.
Window: Remove
Excess Points
This option remove excess points
subject to an error criteria. This process is also known as thinning or
generalisation. The points may have been generated by the Scan or Craw
Digitisers, or you may have created them manually. Before and after screenshots
are shown below.
Before: 154 points
After: 15 points. Pixel Error=1
Pixel Error
This is the maximum permissible error
which you will allow to be introduced by the points removal process. A larger
figure will reduce the number of points dramatically. A figure of one is
generally acceptable.
Remove Points
Starts the points removal process.
You cannot undo this process, so you may like to save your data first.
Menu: Help
This menu provides help, licence registration and the ubiquitous about
box.
Menu:
Help | Find
Displays this help file with the
Topic Find Page displayed.
Menu: Help | Index
Displays this help file with the
Topic Index displayed.
Menu: Help | Contents
Displays this help file with the
Contents Page displayed.
Menu: Help | This Screen
Displays this help file on the main
screen page.
Menu: Help | Technical Support
Takes you to the technical support
on our website.
This is only available to licensed
users
Menu: Help | Geomatix on the Web
Takes you to our main website.
Menu: Help | Licence
Takes you to the licence dialogue.
Menu: Help | About
Provides version information.
Technical
Graphic File Import Formats
The following file formats are
supported.
BMP Microsoft
Windows and OS2 bitmaps
CALS 1-bit image file
DCX PC
Paintbrush Multiple Page
DIB Microsoft
Device Independent Bitmaps
GIF Graphics
Interchange Format
HRZ Slow
Scan Television
ICO Microsoft
Windows Icon
JPG Joint
Photographics Experts Group
MOD:CA Unknown 1 bit
PBM Portable
Bitmap
PCX ZSoft
PC Paintbrush
PGM Portable
Graymap
PIC Pegasus
Imaging Corp
PNG CompuServe
Portable Network Graphics
PPM Portable
Pixmap
RLE Run-length
Encoded BMP files
TGA Targa
TrueVision Files
TIF TIFF
1-32b CCITT RLE G3/4
WMF Windows
Meta-files
WPG Word
Perfect Graphics bitmap files
Please note that some manufacturers
do not strictly conform to the format specifications. Therefore we cannot
guarantee that all variants of the above formats will import correctly. If you
have difficulty in importing an image, try re-processing your image into
another format.
Clipboard Format
Images are saved to and loaded from
the clipboard as bitmaps. Data is saved in ASCII as x and y data pairs
separated by a tab character ASCII (9). Each row of data is separated by
carriage return and linefeed i.e. ASCII(13) and ASCII(10) respectively.