[UE4] Forest-Photogrammetry

spahr

Hey everyone, I thought id jump on the photogrammetry train, try my hand at it. I live in Vancouver so theres great reference here. So Im just trying to put together a quick little scene, nothing crazy, to show off some photogrammetry tests. 

Heres what I have so far, nothing too fancy. Few assets I think turned out well, some that dont(so I try to hide them as best I can). The grass was from some lawn asset I imported from another project, so thats the next thing to go.

Hope to improve my foliage, lighting, and test out photogrammetry. Ive been working in UE4 for a while now, selling stuff on their marketplace, but Ive always had to dumb down the assets and worked under time constraints. Im really looking forward to taking my time, and try to push the engine a little. Doing this part time, so dont expect overnight progress

So point out things you hate, things you like, id love to get tips, a lot of this is new for me. Very exciting stuff. I have some early stuff on sketchfab too if you want to take a look. But I absolutely love this process so far. Heres my progress. And if you have any questions, id be more than glad to answer them.

Cheers

FreneticPonies

Nice work!

gnixon17

This looks great!!! What's the polycount, and will you sell it? If so, I'd love to discuss :pleased:

vassili_zaytsev

Hey,

Very nice stuff! I was just wondering if you would mind sharing what equipment you have (hardware and software) that goes into the making of something like this?

Thanks!

spahr

@gnixon17 No plans on selling this on a store like the Unreal Marketplace. But Id sell it for a flat rate, 100%. Polycounts are not too crazy, rocks sit around 500-2000. foliage is 100-1000. I still plan on making it game ready. LODs, and the whole fixin. I want to make a large forest, much bigger than these screens imply, so optimization will be key.

@vassili_zaytsev I have a pretty nice machine so this process isnt too intense. I have a 980Ti, I-7, etc etc. just spent around 2500 on this not too long ago. The process is basically:

-Take Photos: try to get a photo for every 10 degrees, so 36 all around. could rows works best. I can get 20-30 in a day in cloudy conditions
-Agisoft Photoscan: import, mask, align, build cloud, build mesh, build texture. This process is a tad tedious, and straight forward. The quality is dependent on the photos, you cant really screw anything up in here. set up takes 15-20 minutes, but bakes can take 1-2 hours even on my machine.
-Zbrush: Clean up any holes, and then generate low poly mesh
-**Agisoft Photoscan: If the high poly mesh needed a lot of rework, i bring my newly fixed mesh from zbrush, replace the one in photoscan. then rebake the textures onto my new mesh. 
-Maya: For last minute low poly clean up and UVing
-Xnormal: I use the high poly to generate normals, AO, height, and transfer the base color from hight to low as well. Bakes go fast, I like to use anti aliasing higher for normals so bake times can go slow in some cases.
-**If the model needed clean up, likely the texture will do. So i bring it into substance painter and clone stamp some areas. might even touch up some of the texture, adjust the normals in here. This is more of a preference thing I find.
-Maya: Make LODs, get it ready to import
-UE4: Import and set up material. I have some basic procedural moss, some dirt that uses vertex world space, detail normal map. And I recommend using tessellation or parallax mapping to really let the photoscan information do its thing.

All in all, besides taking the photos, the process takes 1-3 hours(not including bake times). And thats for solid shapes. have a mini rig set up at my home to scan smaller objects. I used it for leaves, which might seem like overkill, but im just trying to learn the process and explore right now, so no work is bad work at this point.

vassili_zaytsev

Awesome man, thanks for all the info. Sorry to bug you one more time but the part I'm the most interested in is the physical camera setup. Do you need a really high quality camera to make this worthwile? Or is it really just the more photos you can shoot the better it can reconstruct your models?

spahr

Well I initially tried without a tripod, and that went terribly. I had to retake some basic photography lessons i had years ago. Remembering with ISO and F-Stop mean. Its pretty basic, and since you try to take photos in the same controlled conditions, you dont need to be some amazing photographer. I ended up buying a tripod but use it more as a monopod.

Try to have the day overcast, with the tripod I can have my shutter speed open longer, so I dont rely so much on ISO. check this chart out. Obviously the better camera, the better the pictures, and the better results youll get with Photoscan. I have a pretty old SLR, and it seems to do the trick. But im so in love with this process im going to definitely fork over the cash to get some top shelf hardware. As far as lenses go, apparently you want a fixed lense, and take photos at around 35 to 55mm. Im no camera expert, so I may be wrong, but apparently a lense that adjusts too much will cause artifacts like distortion or fisheyed look. also, you may set it at 55, but the thing moves and half your images are 55, and half are 70, and that would suck. Also, shoot in RAW format. and thats about it

One thing i forgot in my explanation was delighting. thats pretty important, I havent quite mastered this. Epic has this very very very fancy process where they take their photos with these color palette and spherical ball, then take a panoramic shot to create a skybox around the objec they made. then they can recreate the lighting almost perfectly, this allows them to invert that information, and remove all lighting in the texture. I...use high pass and some dodge and burn hahaha. But because you shoot the images in RAW, you can actually adjust the contrast, exposure in photoshop or lightroom quite easily. and that gets you 80% there. 

Hope that answers your questions.

Things I really need to figure out are making the process better for filling in blank spots missed in my images. faster masking(boy thats tedious). delighting better. And trying to blend procedural material content nicely in engine. The rocks look great, but it may get repetitive, so im exploring ways of making the mats more dynamic.

BenTruong

Did you take pictures of the entire scene, or did you take the pictures of each element in the scene separately(like the rocks and trees) and then place them within the scene?

spahr

BenTruong said:

Did you take pictures of the entire scene, or did you take the pictures of each element in the scene separately(like the rocks and trees) and then place them within the scene?

Each individual asset. There are people who do full scenes, youll see them a lot when people do things like ruins or creek beds. Theres some pretty cool stuff you can do with that.

ZombieDEV

what kind of light you used?

brum

You could try de-lighting by baking out some AO/cavity maps and inverting them, using them to cancel out the dark in the albedo. Of course it won't do much if your albedo is pure black, because then there is no data to regain.