Model size?

Does the 3d model file size produced in DD depend on the number of images submitted or the photo size, or both? I am trying to produce smaller models of buildings for Sketchfab (100mb) but retain quality.

It’s mostly driven by the size (area) of the project and the altitude of the flight. The lower you fly the higher the resolution and the larger the texture files become. In the past I have been able to bring them down a bit by putting the texture JPG’s through a photo program and save them down to 75% quality. It’s barely noticeable in quality and you can go lower, but you’ll have to judge for yourself.

lower?? maybe higher? more area, larger texture? or i’m missing something?

It’s a trade-off. Flying a little higher will reduce the resolution of the textures by having less defined pixels of different colors that have to be taken into account, but your model look/shapes will be less crisp. The same difference between flying nadir-only and including obliques. The are more textures and more faces being applied with obliques, but there’s not much you can do since you have to capture more images. If you are using the textured model i’m assuming you are wanting it really crisp so I think your best bet is to try and post-process the JPG’s so you vertical faces from the triangles still look good. A little bit of all methods (a little higher (220-230ft) , a little less overlaps (75/65) and post-processing saving at 70%) will get you as low as it’s going to go, but an OBJ kind of is what it is.