If you have a photogrammetric dataset (rgb images) and also a model made using a handheld laser scanner, you need to align the model before bringing it into RC for texturing.
You can use many different third-party applications to align the obj's, but in this example we will be using Cloud Compare.
- Make a photogrammetric model of the object in RC, bring in your photos and align them, make a reconstruction, then simplify your mesh down to about 1 million triangles.
- Export your mesh as an .obj and be sure to include the .rcinfo file on export.
- Put your laser scanned .obj into the same folder.
- Open up Cloud Compare, and go to File -> Open, and open up both the RC .obj and the .obj from the laser scanner.
- Double-click on the clouds and name them laser and photo, so you will know which one you are working with:
- Select the laser cloud, and go to Edit-> Normals -> Compute , then select Pre-Vertex
- Repeat this process to calculate the normals for the photo cloud.
- Select the "Laser" cloud, then click on the translate/rotate button on the top toolbar:
- Left click and drag will rotate the cloud, and right-click and drag will translate. Move the Laser cloud just to the side of the photo cloud with the same orientation so you can clearly see both clouds next to one another:
- when ready click the tick to confirm:
- Do not translate/rotate the photo cloud.
- Select both clouds using ctrl and click this button in the top tool bar to align two clouds:
- When prompted to select aligned entities choose Laser and hit OK:
- Now click on a recognizable feature on the laser cloud, and a point labelled A0 should appear. Then you need to click on the exact corresponding point on the photo cloud, and this point should be labelled R0.
- Repeat this process until you have at least 4 Align (A) and their corresponding Reference (R) points:
- Make sure the adjust scale box is checked, then hit align:
- If the alignment looks approximately correct, click the tick followed by OK:
- Select both clouds again, and this time go to this button in the toolbar:
- make sure aligned is laser and reference is photo. If they are the other way around click swap:
- Click OK : The Laser cloud should be called Laser.registered.
- Repeat steps 18-20 now using Laser.registered
- Select the Laser cloud entity (laser.registered.registered), and go to File -> Save, and save to a new folder named aligned laser . We named ours "can.obj" . Now copy the rcinfo file that you exported with the photogrammetric model from Reality Capture, and rename it to correspond with your new aligned laser obj, so ours was called "can.obj.rcInfo". The .rcinfo file stores important alignment info RC can use on import, so the position and orientation will match that of the original photogrametric file we exported in step 2.
- Import the newly aligned obj, in our case can.obj into RealityCapture:You should now have your smooth laser mesh in RC in the exact same position where the photogrammetric model was.
- Unwrap the model to your desired preference:
- Use the Texture Reprojection Tool to reproject the texture from the photogrammetric model onto the model from the laser scanner.