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 |