This tutorial describes the steps to merge 2 or more scans that present overlapping areas. Settings can be changed by advanced users with specific needs.
*Please note that in this case, tasks applicable to results are not needed to be run. They will be run after the merge. The processing consists then in: odometric trajectory computation + loop constraints + navigation constraints (if applicable) + adding GCPs (if applicable).
The scans all have the same non-null EPSG code corresponding to a real-world CRS. For instance, ESPG “2056” corresponding to the Swiss CH1903+ / LV95 projected coordinates system.
Open the “File” menu and click on “Add Project”.
Name your project, the click “Add”.
When asking to choose for an acquisition, do not select any. Instead, click “Skip”.
Right click on the merge project and click on “Set As Active”.
Once the project is activated, right-click on it and select “Add Result To Workspace”.
Select the results previously created in individual projects that you wish to merge and click “OK”. Note: you can select more than 2 results, as long as there are using the same EPSG.
When asked to continue, click “Yes”.
The acquisitions to merge will appear under the workspace item of the merge project. They are in their processed state.
In the “Post Process” menu, click “Loop Constraint Computation”.
Select the line “All Acquisitions” and open the settings.
Choose the following settings.
In the “Post Process” menu, click on “Create Result”.
You can now finalize your processing by colorizing, filtering and exporting the result.
The only difference with a single-acquisition project is that you will have to check/modify the settings of each acquisition in the result.
This is a mixed scenario. One or more scans have the same non-null EPSG code corresponding to a real-world CRS. For instance, ESPG “3949” corresponding to the French Conique Conforme projected coordinates system. One or more scans have relative coordinates (no EPSG, coordinates not expressed with regard to a CRS).
Open the “File” menu and click on “Add Project”.
Name your project, the click “Add”.
When asking to choose for an acquisition, do not select any. Instead, click “Skip”.
Right click on the merge project and click on “Set As Active”.
Once the project is activated, right-click on it and select “Add Result To Workspace”.
Select the results previously created in individual projects that you wish to merge and click “OK”. Note: you can select more than 2 results. However, we recommend adding one by one the results from scans with relative coordinates system. Namely adding one relative scan, align it, then adding another one, align it, etc.
When asked to continue, click “Yes”.
The acquisitions to merge will appear under the workspace item of the merge project. They are in their processed state.
As the scans have different coordinates (expressed with regard to a specific CRS vs relative) a manual alignment is needed to bring the relative scan(s) in the right place before launching the automatic merge.
During manual alignment, 2 scans at a time will be aligned. If you have more than 2 scans to align, repeat the process. For instance, if you have 4 scans:
Any other combination may be valid as long as all the scans are aligned together.
Using the blocks in each of your scan identify 2 common areas (1-3 blocks).
You are going to need to use the “Center View On” functionality to move from one scan to another (right click on an item from the workspace then “Center View On”).
Once done, in the “Post Process” menu, click on “Add Block Constraints”.
To align the scans you are going to need to click 3 pairs of identical points.
Stay with the Constraint type “Relative”.
Click with accuracy one point on the first scan. Using the “Center View On” functionality switch to the second scan. Click with accuracy the same point.
Leave the “Confidence” level at “Default” and click “Add”.
Repeat the operations for another 2 pairs of identical points.
Once you have linked 3 pairs of points, click on “Validate” at the bottom of the “User Constraint” tool.
From the “Post Process” menu, click on “Global Optimization”. Select the “All Acquisitions” line. Then click “OK”.
In the “Post Process” menu, click “Loop Constraint Computation”.
Select the line “All Acquisitions” and open the settings.
Choose the following settings.
Unfold the item “Constraints” in the Workspace. NOTE : each acquisition also contains a “Constraints” item. Make sure to unfold the item outside of the acquisitions sub-items.
Unselect the right check box next to the category “User Constraints”.
From the “Post Process” menu, click on “Global Optimization”. Select the “All Acquisitions” line. Then click “OK”.
In the “Post Process” menu, click on “Create Result”.
You can now finalize your processing by colorizing, filtering and exporting the result.
The only difference with a single-acquisition project is that you will have to check/modify the settings of each acquisition in the result.
Two or more scans have relative coordinates. Each scan starts at (0,0,0). There are no relation to any CRS coming from GCPs and/or Navigation constraints.
Open the “File” menu and click on “Add Project”.
Name your project, the click “Add”.
When asking to choose for an acquisition, do not select any. Instead, click “Skip”.
Right click on the merge project and click on “Set As Active”.
Once the project is activated, right-click on it and select “Add Result To Workspace”.
Select the results previously created in individual projects that you wish to merge and click “OK”. Note: you can select more than 2 results but to make it simpler, you can import only two results at first, align them, then add a third scan, align it, then add a fourth scan, align it, etc.
When asked to continue, click “Yes”.
The acquisitions to merge will appear under the workspace item of the merge project. They are in their processed state.
As the scans have no external reference for proper orientation, a manual alignment is needed to bring them in the right place before launching the automatic merge.
During manual alignment, 2 scans at a time will be aligned. If you have more than 2 scans to align, repeat the process. For instance, if you have 4 scans:
Any other combination may be valid as long as all the scans are aligned together.
Using the blocks in each of your scan identify 2 common areas (1-3 blocks).
You are going to need to use the “Center View On” functionality to move from one scan to another.
Once done, in the “Post Process” menu, click on “Add Block Constraints”.
To align the scans you are going to need to click 3 pairs of identical points.
Stay with the Constraint type “Relative”.
Click with accuracy one point on the first scan. Using the “Center View On” functionality switch to the second scan. Click with accuracy the same point.
Leave the “Confidence” level at “Default” and click “Add”.
Repeat the operations for another 2 pairs of identical points.
Once you have linked 3 pairs of points, click on “Validate” at the bottom of the “User Constraint” tool.
From the “Post Process” menu, click on “Global Optimization”. Select the “All Acquisitions” line. Then click “OK”.
In the “Post Process” menu, click “Loop Constraint Computation”.
Select the line “All Acquisitions” and open the settings.
Choose the following settings.
Unfold the item “Constraints” in the Workspace. NOTE : each acquisition also contains a “Constraints” item. Make sure to unfold the item outside of the acquisitions sub-items.
Unselect the right check box next to the category “User Constraints”.
From the “Post Process” menu, click on “Global Optimization”. Select the “All Acquisitions” line. Then click “OK”.
In the “Post Process” menu, click on “Create Result”.
You can now finalize your processing by colorizing, filtering and exporting the result.
The only difference with a single-acquisition project is that you will have to check/modify the settings of each acquisition in the result.
