Photogrammetry Question

iRoller

I'm fairly new to photogrammetry, and I am curious as to how meshes which aren't visible and finished. For example, you have a boulder and you can see all sides except for the bottom. You take all pictures and make a mesh using Agisoft or whatever your preference. But what do you do about that bottom part which is now just a hole? If you want a mesh to be reusable from all angles, would you just attempt to sculpt it on in zbrush? How would you then go about texturing that part?

JohnnyRaptor

Close the hole, and kitbash some other rocks you photoscanned/already have to add details to the undetailed part, or handsculpt, or a combination of both. Do the same with the textures.

The important part being consistency with the rest of the rockfaces.

thinkinmonkey

Hello iRoller,
yeap, you have to model/sculpt within 3D application you like, yeap, like the old, golden days!
ZBrush has interesting tools, like the one for closing holes.
I could suggest you to use also to use www.meshlab.net which is useful to handle scanned meshes and it's also free for commercial use.
You could copy part of the mesh, modify a little and attach it to fill the hole, then copy texture from another part and bringing there, just use 3DCoat or Painter or any 3D paint program you like.

Just to tell you one thing about photogrammetry and doing things by hand! And I will add... damn!
I'm working on a VR project, my task was (and still is) reconstructing ancient vases shooted in a museum (with their permission) by a professional photographer, who placed vases inside a lightbox to have  a perfect and uniform light condition. The photos are amazing: no specular and almost with the same brightness/contrast.
The problem is that the lightbox creates no useful background for parallax, so it's impossible to reconstruct the vases inside any photogrammetry program, the results were awful! I tried many, but with no good result.
Then I've been asked to reconstruct BY HAND all those vases, something I'm doing right now: with Blender I create the simple, lowpoly form and with 3DCoat I project and clean parts of those photos in order to reassemble the original texture.
Just to answer your question: when something is not reachable, understandable or visible or whatever, well, in that gray area it's you inner artist to come to light.
And a lot of bad words... bad, bad words! >:)