I wrote this answer for one person in RealityCapture forum, but i think this tutorial can be useful for many people.
So, how we should acquire images. Basic rules that work for all modern photogrammetry tools.
First of all, we must remember, that photogrammetry required not silhouette of object but surfaces itself with details (textures).
Now lets imagine simple chair:
It have surfaces that points top, sides and bottom.
So we Must Have at least 1 image directed toward to the every surface.
And not less than 2 images in 10-15 degree to first camera.
Central camera will give you perfect texture. Other two with will give clean Depth mapsfor this Central camera (and later clean Dense Clound) that required for calculation 3D topology.
And this must be for Every surface you want scan! Every surface in ideal condition must have 3 shots.
But if we have surfaces that attached in high degree (90 degree like in example) we need additional images shot for "stitching" Dense Clounds in angles between main camera triplets.
Like this.
"Final" scheme will looks like this:
So we have 15 camera only for 3 surfaces!
Ok, in real world with good camera like Nikon D810 and good lens we can "cheat" and use only 5 camera.
But for this example with 3 surfaces at 90 degree all, even from D810 result will be not perfect.
So i can't recommend shoot less than 11 images
or this will be not enough data for clean depth maps->dense clouds-> mesh, textures, and as result final topology will have less details or will have problem in topology (especially if object have weak surfaces).
And now if we see any nice object that we want to scan, we can plan where and how many images we should have for clean topology and textures.
Also we should remember about real camera and lens. Them can have DOF, aberrations, non linear distortions (last two problems common for area near corners and edges of photo). So real, good data from image is about 75-80% (sometime less) in center of image. And all this can required additional images for good 3D reconstruction.
