Rocks

Another photogrammetry study.

High poly models - photogrammetry, ~11 million triangles each, ~90 photos each (Nikon D5300).

Low poly models - 2510 triangles; 2600 triangles; 4086 triangles.

Software - Agisoft Photoscan, MODO, Substance Painter, Marmoset Toolbag 2.

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My goal for this project was to establish a solid workflow that would allow me to get a game-ready asset from the raw 3D scan in the shortest time possible. You can read my full article about this photogrammetry study on IndieDB.com, for the article in Russian - visit Habrahabr.ru.

I've chosen rocks as objects for this study for two reasons. First and foremost, it's easy to photograph them and get good photogrammetry results. Second, it's easy to make finished game assets out of them, you can make several of them in the row very fast, therefore you can establish your workflow faster too. Although only three stones are presented here (the most interesting ones), I've made total of nine rocks during this study.

My main concern with photogrammetry of rocks in nature was the fact that there is no way to get full 360 degree 3D scan. One side of the rock is always buried into the ground and obscured, thus you will always get a hole in your model's mesh and problems with placing this model on the game level in the future.

To solve the problem described above, I've decided to photograph the stones in my "studio" (aka my flat). My plan was to make top quality photogrammetry of small stones and then use them as large rocks in-game. In the end my plan worked perfectly, especially with extra layer of "detail" textures on final models.

After using a special stand and new lighting, I was able to achieve highpoly with completely closed surface and excellent quality, therefore no extra time in Zbrush for a mesh clean-up was needed. I've used raw 3D scan straight for baking maps.

At first I've decided to make retopology manually to get full control of model's surface and optimisation. But I've quickly proved myself wrong. Since natural objects possess chaotic structure I've switched to almost completely automatic retopology, with few manual adjustments here and there. It's saved me a lot of time.

Stone material is fully nonmetal, so I went with metalness PBR workflow (instead of specular one) to use less texture memory. Rougness map and adjustments to other maps were made in Substance Painter.