Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: barrubba on 2019-12-09, 00:35:11

Title: corona camera texture distortion
Post by: barrubba on 2019-12-09, 00:35:11

i have a 180° panoramic photo and it must be used as background in 3dsmax to place a solar farm project
The problem is that the focal is wrong becouse of huge field of view of panoramic photo.
I think to resolve using distortion texture setting in corona camera, right?
what kind of texture i have to create to reproduce that distortion, in order to render correctly project placement and perspective?
Last step will be post processing in photoshop where merge both image and rendering.
Thank you

Title: Re: corona camera texture distortion
Post by: GeorgeK on 2019-12-09, 08:27:22

Hey, is this what you are trying to achieve? (see attached)

Title: Re: corona camera texture distortion
Post by: barrubba on 2019-12-09, 08:46:04

No.. The panorama is not a spherical 360 photo but a 180 degree panorama, obtained merging several photo in ptgui software.
I have either another panorama of 120 degree.. And even in that case I need to create correct (or approximated) distorsion map

Title: Re: corona camera texture distortion
Post by: romullus on 2019-12-09, 10:18:39

Hi,
Your bacplate has cylindrical projection, not spherical. Corona supports both, so instead of spherical, choose cylindrical.

Title: Re: corona camera texture distortion
Post by: barrubba on 2019-12-09, 11:03:41

this is cylindrical but its unusable...i intend something similar to barrel distortion
https://www.google.com/search?biw=1536&bih=718&tbm=isch&sxsrf=ACYBGNSnU0vVG64ftr9wA9ZPv6ohBTHAgg%3A1575885668200&sa=1&ei=ZBvuXe7xC4usUpjhvPAJ&q=barrel+lens+distortion+map&oq=barrel+lens+distortion+map&gs_l=img.3...133076.134593..135063...1.0..0.151.1197.2j8......0....1..gws-wiz-img.......35i39.7YPtjw6Vaf8&ved=0ahUKEwjus9bLp6jmAhULlhQKHZgwD54Q4dUDCAc&uact=5

Title: Re: corona camera texture distortion
Post by: romullus on 2019-12-09, 11:18:24

No, barrel distortion is entirely different thing, it absolutely has nothing to do with projection. Your last example is partial spherical (most likely) projection with unleveled horizon. First you need to level horizon and then proceed with the rest.

Edit: changed some wording, to be more clear.

Title: Re: corona camera texture distortion
Post by: barrubba on 2019-12-09, 12:32:25

i'm not a specialist! so the final job is to fit corona camera perspective/lens distortion with the one you can see in photo i0ve attached in original post.
It's not important the process but the results..i0m ready to do everything but imho horizon leveling is not so important as the rest..

Title: Re: corona camera texture distortion
Post by: romullus on 2019-12-09, 14:56:24

Hm, i didn't realise that Corona camera doesn't give you an option to adjust horizontal FOV and always renders full 360. That complicates things a little bit, but i think it's still doable. You just need to cheat a little and pretend that you have full 360 backplate. I'm attaching quick attempt to match perspective. It's not perfect match because backplate's horizon is not leveled. Once you level the horizon, you should be able to achieve much better match.

Title: Re: corona camera texture distortion
Post by: barrubba on 2019-12-10, 11:59:07

How did you "cheat a little" ? with camera distance from target and fov?

Title: Re: corona camera texture distortion
Post by: romullus on 2019-12-10, 12:08:55

I just "added" missing horizontal degrees by setting bitmap's U tiling to 1,9 After render, you will have to crop what's not needed, or just render a region.

Edit: don't forget to multiply output horizontal resolution by 1,9 otherwise aspect ratio will be wrong.

Title: Re: corona camera texture distortion
Post by: maru on 2019-12-11, 14:47:12

Another idea would be to apply this photo to some cylindrical/spherical geometry and use it as background, right?

Title: Re: corona camera texture distortion
Post by: barrubba on 2019-12-11, 16:09:17

i need to ha(ve that background yet cylindrical panoramic, even if not perfect, and to work on barrel effect of 3d rendered model, to fit with background sphericity perspective

Title: Re: corona camera texture distortion
Post by: romullus on 2019-12-11, 17:31:53

Did you manage to achieve satisfactory result?