Help with AI shadowmatte in Maya

Discussion started by 3dmeshes

Hi, where exactly can you adjust the shadow, i.e. just make it lighter or darker. can't be that complicated :/ thanks Enrico

Answers

Posted 25 days ago
1

your going to need to be more specific, what render engine, what is your lighting setup etc.

Generally speaking - shadows are usually a result of the global lighting environment, so if thats a dome light as an example you can control the shadow intensity by adjusting the gamma of the light.

Posted 25 days ago
0

O.k. setup is:

AiSkydome -> load Hdri -> make plane -> Ai shadow matte -> Arnold Renderer

the shadow doesn't adapt to the hdri, it always stays the same i can't use another light like e.g. spotlight

Posted 25 days ago
0

I dont use maya/arnold but the principle should be the same. When using a HDRI is there a node you can plug in to control the gamma of the image? This will lighten/darken the shadows.

Posted 25 days ago
0

I've tried a lot and since this morning I've watched countless videos on youtube, no video can help. as I said, I only want to make the shadow lighter or darker and not the model!

3DCargo wrote
3DCargo
you need to compensate, when you adjust gamma you need to do the inverse for the exposure, thus model stays the same brightness, shadows become darker (all shadows - hence "global" illumination). Photographic principles. You can see in this example I made (I went to extreme value so you can see). The shadows get much darker, where there is no shadow (on the seat/lower armrest its still the same values) https://ibb.co/SswV72t . Alternatively use 2 environment lights, 1 with the lighting you want for the chair (lets say the original image on the left I posted), and one with the dark gamma (for shadows on the floor), then include/exclude the dark one for including floor shadows, include/exclude the light one for including only chair illumination/self shadow - https://ibb.co/DGnVT4H
Posted 25 days ago
0

After a quick look, try plug in a gamma correct node before your HDRI.

As I said - shadows are the result of global lighting. Which means you need to control the gamma of your image (if using a HDRI) to push the black values up/down (light/dark). This is fundamental knowledge, not program specific.

Posted 25 days ago
1

Yes, I try around in the settings but it doesn't work, and if I add another light, nothing happens, Maya is a little different

3DCargo wrote
3DCargo
I use blender, c4d, houdini, 3dsmax and have used maya about 10 years ago - the principles are all the same. The tricky part is working out how to replicate it using the tools in Arnold. They will be there its just a matter of thinking about the problem as a method, the first method is you need to darken the gamma of the HDRI, the second method is you need 2 HDRI's to control separately to keep the self-shadows/illumination on the chair the same. The principles of global illumination are different than those of previous methods, the hint is in the name "global". You need to control the shadow globally - then split it in your case (1 HDRI for the chair gamma, 1 HRI for the floor).
Posted 25 days ago
0

Have you tried this with multiple HDRIs? Some HDRIs cast strong shadows and some cast soft shadows.

3DCargo wrote
3DCargo
While that's true, it doesn't negate the issue for the OP (if the OP darkens the shadow it darkens it also for the chair). If anything I would advise keep the HDRI the same for the purposes of testing or you overload your variables. You can also do as I'm suggesting with the gamma for HDRI's that have less intense shadows to create a darker/more intense shadow - its a universal method.
Posted 25 days ago
0

I play with all settings but nothing happens :/ can someone please explain to me how i can adjust the shadow of my background image with shadow matte in maya, setup is above

3DCargo wrote
3DCargo
I honestly recommend you use some standard render engines - you will see improved sales. Vray is a pretty solid render engine to provide your models in as well as what you currently offer. You will also find the same method that I mention above for your presentation.
Posted 25 days ago
0

soo, so! you cannot change the shadow. But you can render the shadow separately and edit it in Nuke or Photoshop, for example.

3DCargo wrote
3DCargo
Well that's always an option using AOVs / render passes. If that works for you job is done. I did see in Arnold there is an AOV Light Group Manager, you could probably do include/excludes through that if its worth your time.
Posted 25 days ago
0

@3Dcargo I agree! but I'm very disappointed with Autodesk for offering something like this. the scene setup can be done in a few seconds, but you can't change the shadow? so it's all just a joke and useless, what's the point? I've emailed Autodesk and am still waiting for a response from Autodesk support. I'm mad, have a nice day!

3DCargo wrote
3DCargo
You can change the shadow. I just checked Arnold in 3dsmax, same settings as maya basically just ui is different. You can create 2x Arnold skylights, then create 2 HDRI textures - 1x for the object 1x for the floor. Set the gamma for the floor HDRI. Then for each object use an "Arnold Properties" modifier (whatever that translates to in maya), then you can include/exclude lights/shadows per object. Remember that adjusting the gamma for the floor HDRI will brighten the floor while darkening the shadows so it will bounce more light up, you can counter that using the include/exclude in the object properties or override the GI light bounce. https://ibb.co/0ZHqSWS . If you don't have "Arnold Properties" then see if this helps, maybe you can use light linking instead https://youtu.be/LUv_yKdXEWQ
Posted 24 days ago
0

OK. the error is and that's a little crazy. only load the spotlight and then only the aiskydome and it works. I only load the aiskydome and then the spotlight, nothing happens on my system I can adjust the shadow with the spotlight, everything works great.

Posted 24 days ago
0

@3dcargo thanks for the video link, it wasn't shown to me during my search

3DCargo wrote
3DCargo
So light linking did the trick?
Posted 24 days ago
0

well this video has now contributed to the solution but steered me in the right direction. I take this sequence: Arnold -> Render Settings -> AOVs -> shadow_diff -> Photoshop -> substract this technique is enough for me to adjust the shadows of the image background exactly.

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