V-ray car rendering help


#1

I’ve been working on this project of car studio render, using around 8 different lights, everything’s been working fine and till now I’ve rendered 4 different shots but in this one I can see at some places on the ground some block shaped artifacts I guess? I don’t use v-ray much and just decided to start learning it so this is one thing I haven’t been able to figure out, I’ve tried changing lighting, materials, remapped uvs, changed render settings but can’t really understand why I’m getting this.



If you look closely, you can see some blocky shaped spots there.


#2

They are very faint, but I’m not sure how you would fix this without a lot more work and render-testing. I imagine you’ve plop-rendered those areas while changing settings to no avail?

Since these are just shadow-areas, can you fix it in post? Can you blend it in Photoshop or something?


#3

I am guessing this has to do with “the position” of your HDRI image and Lights…

Here is a image of what I am trying to say…

As per my image - in 3d space around 4 shadows would be created on an object with 2 hdri light sources and 2 vray lights. I guess you understand now where the extra shadows would come from…

1 - Render out an image with only your HDRI (Switch off other lights)…
2 -Render an image with only your scene lights (Switch of your HDRI source).

Post it here, If I am wrong about this we could get a better insight at what exactly is causing these shadows.

The Solution -

Place your lights exactly in the direction where your hdri lights are with 0,0,0 as center…

Just like in a day scene - How they match the vray sun to hdri…

Here is a link to explain better about a single light source in HDRI and and a Single vray light -

https://vimeo.com/57433530

I am afraid since you are using 8 light sources - you would have to align 8 cameras as per the tutorial and place your lights exactly where your hdri image’s light sources are.

Note - Use same number of lights as per your hdri image.

Do post your renders… would love to help :wink:


#4

No I didn’t plop rendered those areas I setted the whole scene with ipr render first, this was a complete render without any messing around with settings in between, I did tried changing light positions and all but didn’t help.


#5

Thanks for the explanation, I understand what you are explaining me here, I did use an hdri first but it was just for setting materials and all, I turned it off because I coudn’t exactly get the output according to my preference and so I set the whole scene with v-ray lights only, without any hdri, but yeah I’ll give it a try with different camera angles and see if it works, though it should work I think because its rendering just fine with other camera angles.


#6

@Pinokio28

I think he is talking about the bucket like artifacts (edges perfectly horizontal and vertical) that are visible very faintly.

@Akshat Sharma

Are you using buckets at all (as image sampler or in the irradiance map)? Do you use distributed rendering?


#7

Yeah I am using bucket sampler, shading rate is 2 but no, I’m not using distributed rendering


#8

Have you tried using the progressive sampler? Does that make any difference?


#9

Sorry, I was out and wasn’t able to check the forum for few weeks, so I as you said, I gave progressive sampler a try and while the spots were still there, they were very few, I guess I should change settings accordingly now that it indeed is an issue related to render settings.


#10

NP! It seams like a bug either way, and if it’s still present without using buckets, even if faintly, your best course of action is probably to head over to the Chaos Group forums or contact them directly.


#11

you can try hdrstudio light it is more professional car rendering


#12

Yeah It’s a nice plugin, I tried it once some time ago but this project was just for more of a practice purpose as I was trying out v-ray.
anyways… I’ve solved the problem and it indeed was related to the bucket rendering specially because of large bucket size so reducing the bucket size did solved the issue.