A poor man's photogrammetry workflow

[BBB3]

I wrote this little guide yesterday. Maybe someone finds it useful.

http://bertrand-benoit.com/blog/the-...hotogrammetry/

[joconnell]

I put it as a comment on your facebook page but it'd be useful here too. The only thing on shooting the images is with smaller apertures, chromatic aberration starts to have a greater effect so for things that you're shooting up close, you don't need all of the depth of focus that f22 gives and you might get sharper edges from a slightly wider aperture. You've to do a test of your lenses on something with fine detail close and far away to see how much bloom / fringe appears at each aperture for the best results!

[BBB3]

That's a good point. I'm actually not on Facebook, so I saw the comment but couldn't reply.
It's true that for CA, the sweet spot is really around F8 for my lens. On the other hand, there's quite a lot of blurriness at that aperture, and this makes the scanning (and above all the texturing) a lot harder. Even F22 is not entirely sharp when one is so close to the object. So in my case, I decided to go for sharpness to the detriment of CA (and CA is more visible at the edges of the image, which doesn't affect the object in the center).

[joconnell]

I could be completely wrong (will check my jeffrey ian wilson stuff) that some of the scanning software discards things facing away from camera so it might not be an issue?

P.s. the recent tree tests look great!

[AJ Jefferies]

Ha! I use the *exact* same setup and process - even down to the Ikea cheeseboard! Makes me feel less silly to know someone else is doing it this way too.

Great write up Bertrand.

[BBB3]

Great minds, you know...

[Bathyscaph]

Good stuff. Thanks for posting.

[chriserskine]

that mask by object looks like a great feature.

thanks for the write up.

[samuel_bubat]

Great guide. Talking about "poor" man´s workflow. If one doesn´t own ZBrush I recommend this little beauty.
https://github.com/wjakob/instant-meshes
A free auto retopology tool with awesome results. Even works pretty solid for multimillion poly meshes. I do the mapping and texturing in max using pelt mapping and render to texture. Attached is a screenshot of statue reduced from 10 million polys to 20k and a normal map of 1500px (rendered in UE4). Also it support command line processing so it can be called from maxscript to automate the process. Btw. if you want to use this and you export and obj from max the "relative numbers" switch in the obj exporter must be off.

[vlado]

How well would this work for stuff like trees and grass?

Best regards,
Vlado

[BBB3]

@Vlado, not sure if your question relates to photogrammetry or to samuel_bubat's post about instant-meshes.

While it's of course not possible to scan a field of grass or an entire tree, I've played a lot with scanning discrete parts of vegetation and use them as building blocks in something like GrowFX. You can scan bark and turn it into a tileable texture relatively easily. You can scan an entire tree trunk very easily. And you can scan leaves (although the worklfow for scanning objects without thickness or volume is a little more complicated in my experience). All these yield good results in themselves and you can bring them together in a GrowFX tree easily.
I guess you could scan grass the same way but I'm not sure you would want too since existing workflows for grass are already very satisfactory (while no-one yet has completely nailed the photorealistic tree).