In this status section, the functions are available to edit the tiepoints of the current project: Point Detection Point Matching Manual Measurements Listings
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This method determines the best points in each image, to be used for matching with points in other images. The determination of these points is done in function of a number of parameters as you can see in the following dialog. This dialog show the list of all the images in the project and the number of already determined points. When no points are detected yet, a question mark '?' is shown.
Steps per octave scale
This scale is default set to 1. This scale influences the difference in ground height. '5' means that there is a big difference in'flying height-ground height' on different photo locations.
Image size
This value is default set to 'Half'. This parameter influences the speed of detecting. The lower the size the faster the search will happen. Take into account that the lower the size means that the detail level of searching will be downgraded.
Size of the sub image
This value is default set to 'Normal'. This parameter influences the speed of detecting. The lower the size the faster the search will happen. Take into account that the lower the size means that the detail level of searching will be downgraded.
Number of points to detect
This value is default set to 'High'.
Detect
This function starts the detection procedure:
Delete
This function deletes the detected points for the selected images.
View
This function shows how the points are spread over an image.
This will open a dialog showing the image as you can see in the next view: You can run through the points using the next and previous arrow above the image.
Refresh
This button starts refreshing the values in the column 'Point Count'.
When the button becomes sensitive again, this process is finished.
Stop
Pressing the 'Stop' button
Sometimes it is interesting to have a look at an image to see the points that are used for matching. Selecting this menu function, opens a dialog containing a list of all the images:
After the detection of points in each image, the purpose of this function is to find out which points match between the images. This is done using the next dialog:
Minimum model-overlap tiepoints
This parameter sets the minimum number of tiepoints that have to be found between each model.
Maximum model-overlap tiepoints
This parameter sets the maximum number of tiepoints that may be found between each model.
Minimum strip-overlap tiepoints
This parameter sets the minimum number of tiepoints that have to be found between overlapping images between strips.
Maximum ratio between best match and second best match
This parameter sets the maximum ratio between the best matching points and the second best matching points.
Minimal pixel distance between matches
This parameter gives an important indication about the spread of the matched points.
Translation+rotation between matched images
This parameter allows that the images are in crab (e.g. fixed wings).
Find
There are several ways of finding the matches:
Pressing the 'Find' button starts a search for matches. All possible image overlaps are being checked, model- as well as strip-overlaps, on basis of footprint overlap. These 'Find' procedures are all multithreaded and take full advantage of your PC's capabilities. It is advised to have high RAM volume, multiple cores and a 64-bit operating system.
During the 'Find' procedure, the matches are listed per model in the dialog as follows: The line selected above shows that we have found 12 matches in model 4-5. The name given to the point measurements creating 'a' match between the different images, are identical in these images. All the 'Find' buttons stay insensitive as long as the procedure is running or the 'Stop' button is pressed.
Find in Model
This second find procedure starts looking for matches only in selected models:
Before starting the find-procedure using the button 'Match Selected', you have to propose a set of models to the procedure. To select the models you have two possibilities:
After having selected the models, press the button 'Match Selected' to start the find-procedure in these models.
The matches will again be listed in the dialog as described in the above described 'Find' paragraph.
If the matches are interesting for the project, don't forget to add them to the Strabo project as described in the 'Add points' paragraph.
Find between strips
This third find procedure starts looking for matches only in strip-overlapping models:
Before starting the find-procedure using the button 'Match Selected', you have to propose a set of stereo-overlap models to the procedure. To select the models you have two possibilities:
After having selected the strip-overlap models, press the button 'Match Selected' to start the find-procedure in these models.
The matches will again be listed in the dialog as described in the above described 'Find' paragraph.
If the matches are interesting for the project, don't forget to add them to the Strabo project as described in the 'Add points' paragraph.
Add Points
These matches (or tiepoints) are not added to the project yet. When can you add these points to the project?
To add the matches of your choice to the Strabo project:
View
Using this button it is possible to have a look at the matches:
You can run through the points using the next and previous arrow above the image. You can remove an error out of the list.
Stop
The 'Stop' button, takes care of stopping the 'Find' procedure. All running threads will be allowed to finish, all waiting threads will be canceled. After stopping the find-procedure, all find buttons become sensitive again.
Selecting this menu function opens the next dialog containing a list of a all the tiepoints or matches. This dialogue provides the functionality to view and edit all the matches manually. Next to a number of new functionalities you can also see:
Show
This function shows where a selected tiepoint is located in the Orbit GIS canvas.
It will show a rough localisation of the tiepoint. Keep in mind that a tiepoint is measured in several images and as such is represented by different crosses on the screen.
Use the Strabo Preferences to toggle the tiepoints visibility in Orbit GIS.
Refresh
This function refreshes the list of tiepoints.
Edit
After selecting the tiepoint of your interest, the 'Edit' button opens a window containing a number of subwindows.
Each subwindow shows the tiepoint measurement (or match) central in the image: Using the subwindow's functionality you can easily view, delete and edit the selected tiepoint manually. It is possible that different crosses are visible. This means that other tiepoints are measured in the vicinity of the selected tiepoint. You can switch on the tiepoint names using the toggle 'Show tiepoint names' in the 'Tiepoints …' dialog.
Rename
If you need to give another name to a selected tiepoint, you can use this function.
You can now enter a new name and press 'OK' to accept. All the corresponding tiepoint measurements will be given the new name.
Delete
All measurements of the selected tiepoint will be deleted throughout the whole project:
Select Singular
It is a condition for all tiepoints that they must be measured in at least 2 images. If a tiepoint is measured in only one image, it is a singular point.
This function 'Select Singular' will select all the tiepoints that are measured in only one image. They will be visible in the blue selection color.
Show tiepoint names
This toggles the visibility of the name in the 'Edit' tiepoint windows.
Search Tiepoint
Under the 'Show tiepoint names' toggle, there is textfield, enabling you to select a point of which you only know the name.
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This function provides the possibility to measure tiepoints manually. The next dialog will popup containing a list of all the images in the project:
The software proposes a unique tiepoint name. You can now either:
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This menu functions is a convenience function helping you to easily measure manually different missing tiepoints. This function pops up the next dialog. The dialog lists the models or strip-overlap models where matches are missing in correspondence to the given minimum number of tiepoints between models and strip-overlap models. Selecting the model opens a similar dialog as described above in the paragraph 'Measure tiepoint (manually select photos) …', ready for measuring the remaining missing tiepoints.
This menu function creates two text files. The files will be saved next to the Strabo project files:
This function lets you select a file containing observations, to be imported in the actual project. See the next paragraph on the requested format.
For the purpose of exchange of measurements between different Strabo projects, you can save all the observations made in all the images with this function. Selecting this menu function will create two files containing the same information: