3D model to RTI

[Nicolas]

Hello,

I am interested in RTI and I have started to use the method involving 2 spheres.

However in some case, there are physical difficulties for taking photos.

I would like to know if I create a 3D model (with an Artec Scanner by example), is there any applications to convert 3D model to RTI ?

My 3D model is of course of a surface.

 

Regards

 

Bremard Nicolas

 

[KurtH]

Late to respond... I'm gonna say yes and no. You cannot easily create a true RTI file from a 3D model, however it is possible to compute the surface normals of the faces of a mesh, and the normals will provide some relighting capability in viewers similar to what you'd expect from RTI (and other photometric stereo related) representations.

The issue is that one of the advantages of RTI is you get a value at every pixel location of the photo. If you take a 3D model, it's usually lower resolution than a high res still image, so you end up with a lot fewer normals.

That said I've been doing very high resolution photogrammetry and structured light scanning with models on the orders of hundreds of millions of faces. In agisoft MetaShape (and maybe some other programs) if you decimate a mesh you can build normal textures, you get a much smaller mesh that is more reasonable to put into an online viewer (eg: sketchfab, Smithsonian voyager, 3D Hop) or a 3D rendering tool (Blender, 3Ds Max, Cinema 4D, Keyshot, Adobe Substance Stager) and wrapping the model with the normals gives the impression of proper relighting with a much smaller geometry that doesn't bring computers to their knees. That said I haven't found an easy way to bring such data into the RTI viewer in a way you can use.