Combining Multiple PS Scans

This document is a tutorial that demonstrates one method to acquire and combine two cylindrical scans. Although this document was created with the Cyberware Head & Face Scanner in mind, the procedure is easily adapted to any other Cyberware scanner.

This guide is not intended to be a comprehensive listing of commands and button presses. Nor is it intended to be the sole guide to completing this process. There is another solution, but it is not suited for inclusion in this tutorial, due to the length of the process. Please refer to the CyEat Editing user guide, Multiple Meshes section, for more advanced alignment techniques.

Sample Files

If you would like to work with the sample files used in this tutorial, you may download them from here:

Procedure

1. Launch CyDir.

CyDir

2. Create two folders in which to store the scans. For the purposes of this guide, call them scan1 and scan2.

CyDir - Two Folders

3. Open both folders in the CyDir windows by pressing the white arrows next to the folder names.

CyDir - Two Folders Open

4. Minimize CyDir by pressing the Windows Minimize button in the title bar. You will use CyDir later in this process.
5. Launch CyScan by clicking on the CyScan icon or by selecting the icon from the Start menu. Do not use the Scan buttons in Guee. You should now see the CyScan window, similar to the illustration below.

CyScan

6. Press the Setup button at the bottom-left of the CyScan window. This will open the Setup Scanner window.

CyScan Setup Window

7. Adjust the scan parameters to meet your needs. For the purposes of this example, we will use the following:

Texture	Arc	Pitch
RGB	360	0.70°

CyScan Setup Complete

IMPORTANT:
Please note that the parameters in the Setup window MUST be the same for each of the scans that you wish to combine. If these settings are not identical to one another, the automatic alignment tools may not provide the best results and the data may have noticable artifacts.

8. Home the motion scanner by selecting 'Scanner | Home'.

CyScan - Scanner Menu

9. Position the subject accordingly for the first scan. Ensure that the subject is well centered on the motion platform.
10. Press the Scan button to start the first scan.

CyScan - Scan Button

11. Verify that the scan is acceptable in quality.

CyScan - First Scan

12. Save the scan in Echo format by selecting 'File | Save as Echo...'. Give this scan the name of "scan1/scan000".

CyScan - Save As Echo...

IMPORTANT:
The naming of the scan files is very important. If you do not use the name, scan000, for BOTH of the scans, this procedure cannot be completed successfully.

13. Reposition the scan subject for the second scan. Verify that the subject is centered on the motion platform.
14. Press the Scan button to start the second scan.

CyScan - Scan Button

15. Verify that the scan is acceptable in quality.

CyScan - Second Scan

16. Save the scan in Echo format by selecting 'File | Save as Echo...'. Give this scan the name of "scan2/scan000".

CyScan - Save As Echo...

IMPORTANT:
The naming of the scan files is very important. If you do not use the name, scan000, for BOTH of the scans, this procedure cannot be completed successfully.

17. Bring the CyDir to the front of your desktop.
18. Click on the Merge button in the small scan1 window. The CyPie program will now open.

CyDir - scan1 Folder

Typically, CyPie is used to merge multiple linear scans of an object. In this case, you will be using CyPie to turn the single cylindrical scan into a polygonal mesh. This new file will be used to align to the other mesh (in the scan2 directory).

CyPie

19. Click on the All button, if you need to edit the scan. Perform any sort of editing that you require, then click on the Continue button to accept the editing. CyEdit will save the edited file into the scan1 folder automatically.

CyPie - Edit All

20. In the CyPie window, click on the Merge button. The scan will be converted into low-, medium-, and high-resolution polygonal meshes. These meshes will be used in the alignment process, later in this tutorial.

CyPie - Merge

21. Click on the Merge button in the small scan2 window. The CyPie program will switch from the scan1 to the scan2 folder and load the original Echo scan file from the scan2 folder.

CyDir - scan2 Folder

22. Click on the All button, if you need to edit the scan. Perform any sort of editing that you require, then click on the Continue button to accept the editing. CyEdit will save the edited file into the scan1 folder automatically.
23. In the CyPie window, click on the Merge button. The scan will be converted into low-, medium-, and high-resolution polygonal meshes. These meshes will be used in the alignment process, later in this tutorial.
24. Click on the Exit towards the bottom of the CyPie window. You will not be using CyPie for the remainder of this tutorial.

CyPie - Exit

25. Click on the Align & Merge button. CyEat will start up with the low-resolution meshes for each of the two scans loaded.

CyDir - Align & Merge

26. Click on the Guess button in the CyEat window. CyEat will try to guess the initial alignments of the two scans. Sometimes the guess is accurate and sometimes it is not for this type of procedure. You may be forced to align the two scans manually. If so, please consult the CyEat user guide, specifically the section for Advanced Aligning, for more information on the manual alignment process.

CyEat - Guess

27. Evaluate the alignment. For this type of project, it is doubtful that CyEat will be able to work out the best alignment. You have two choices:
    1. Adjust the refine alignment parameters. For this type of project, it is helpful to skip the first two stages of the refinement.
    1. Click on the first two checkboxes under the Refine button. This will deactivate the first two alignment iterations. Doing this will prevent the software from destroying any manual alignment that you may have completed.
    2. Proceed directly to the next step.
    2. Leave the refine parameters at the default.
28. Click on the Refine button and the two meshes will be aligned further.

CyEat - Refine

29. When the two low-resolution meshes have been aligned to your satisfaction, click on the Final button. The two medium-resolution meshes will be more accurately aligned as a background process. When that process is complete the two aligned medium-resolution meshes will be displayed for your evaluation.

CyEat - Final

30. Click on the Merge button in the CyEat window.

CyEat - Merge

31. Click on Exit button to leave CyEat.

CyEat - Exit

32. Click on the Exit button to quit CyDir. The final merged polygonal mesh has been saved as hires.ply in the parent folder of scan1 and scan2.

CyDir - Exit

Known Problems

A slight change in facial expression is possible between the two pairs of scans. If the two meshes from these scans are merged you may get two surfaces, or at least some strange depressed or elevated regions, over those parts of the face where the difference is greatest.

One solution is to void out the face from the second scan. Most likely, you are only using the second scan to get areas missing from the first scan (e.g. top of head), so you don't really need a second face. One problem with this approach is that you may not have enough common surface to align the two scans.

Another solution is to force CyEat to merge the two meshes together even if they aren't particularly well aligned. On the top row of the CyEat window is a blue right arrow; click on this and you get the "CyEat Controls" window. Change the "Dist" value to something like "2.0" sometime before you select "Merge" to merge the meshes together. By increasing the "Dist" number you are telling CyEat to merge together surfaces even if they aren't particularly close.