how to get a more realistic render using vray

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  09 September 2017
how to get a more realistic render using vray

Alslamu Alikum (Peace be upon you.. )

I was kindda wondering what do you think about this renderimages and whether if you could help me get better results for the render of
this scene.. actually i've hardly got to this result via adding displacement
map and HGlossiness to my materials which raised by result rendering time
enormously and literally made Max and the whole system freezes (it took cam_2
24min and 15sec to render a 800x600 pix preview).

the thing is that i actually saw tutorials about addingmaterials to a scene and it got better results with way less settings than i
had to this one so i think there must be something wrong with my scene that
needs someone else to critique.

Scene's archive on Google Drive

any thoughts would help.. appreciate it and thanks in advance
created with : 3ds Max 2016 - vray 3.2
PS: these are raw renders as it came from Max and were not retouched by any mains in Adobe Photoshop
  09 September 2017
I actually think the image looks pretty good as it it. My main critique would be the wooden slats that you sit on. They have been modelled into the chair base itself, and usually they would be separate pieces nailed/glued together. This is making the box UV mapping look a little strange like it's veneer that has been glued over the sides.
Other than that, things look pretty good. Perhaps a little too many lights for a such simple scene.

1x VRay Sun
2x VRay lights
1x VRay dome light

A three point lighting setup would work just as well.

What system are you using? I opened your scene and set off a render of cam2 with all the settings you provided and the render finished at: 2m 52.9s. My system is first generation i7 so it's quite dated now.

Your VRay lights have their sample settings to 16 for each light. Due to the VRay sun there really isn't many shadow areas for area lights to generate noise, so you might get away with toning the samples down.

I also switched off the bump channel, as rendering with just the displacements gave exactly the same output as your image. Bump is not much in the way of calculations on a mesh like this, but it's certainly not needed.

Generally speaking I really think that it's realistic enough, apart from the specular. This chair is quite rough and I assume you have gone for the "varnished" look. You have pushed the reflective IOR to 8 to really push out the highlights. Wood is a soft material which blurs specular reflections. The highlights on your render to me would be a varnished surface but the displacements say different. Varnish generally has an IOR of 1.5 - 1.57. Sure your going to get much less reflections but you can work from there.

The 2 images are as follows. The first one is a straight render from your scene with no changes.
The second I have changed:
Material: The refection samples back to 8
VRay lights: All 3 back to 8 sampling

Reflection map removed from HGlossiness and placed in the RGlossiness channel.
Reflection swatch set to dark grey.
HGlossiness to 0.66
RGlossyness to 1.0
IOR to 1.5

The result is a lot less refective but looks more absorbent as I would imagine semi-rough wood to look.

My Houdini Tutorials
  09 September 2017
Just to add. If you wanted a clear coat on this, that's quite easy to do. Ignore the funky reflections, the only thing this has to reflect is the 2 huge VRay lights from the front and left. You can see the displacements of the wood are still there but under a clear coat that is not displaced. The chair also keeps it's own specular as well. This could be done in a single shader but for ease of setting up I cloned the chair, added a push modifier of 0.001, and a shell modifier of 0.05mm.

Simple material setup.

Highly refractive material with a black diffuse as the main shader inside a VRay2sidedMaterial, with the transparency colour set close to black.

I can re-upload the scene file for this if you like.

Notice the rendertime has now doubled.

My Houdini Tutorials
  09 September 2017
i can't thank you enough Glenn for your time and everything you've said and the tips for the 3rd render you kindly added..
you are right about how i wanted to get a varnished look for this material but i think i wasn't looking for the varnished look exactly rather than a deeper look makes me get to the point where i can't tell is it actually a rendered scene or a real photograph for this chair, this is why i went that far as for specular settings thinking that maybe this is the problem.

my system is :
- core I5
- ATI 1gb graphic card
- 8 gb ram
- win 8.1
- laptop "Dellnspiron n5010"

i really admire how u simply got to that very specular effect at the 3rd render but i think i would go for the effect in your 2nd render by the will of Allah..

i'll tweek these settings to the one's you've mentioned and hopefully render time is reduced as well as getting that beautiful look cuz if it didn't i'm not quite sure how will i get a higher resolution render if it takes 20mins for rendering a 640*480 pix.

sure i'd love to have a copy of your file if it wouldn't be to much trouble for you..

again i can't thank you enough for everything that you did to help me..
  09 September 2017
No problem. Glad I was able to help.
Just remember that using lots of sampling for a ultra clean image is not always the way forward. It's a balance between noise and rendertimes. Get the noise to where you are happy and leave it. Otherwise you will be adding huge rendertimes for not much bonus for image quality. Remember that noise is almost unseeable in direct light, it's just the indirect light, shadows, reflections where the noise lingers.

Here is the file for you.
My Houdini Tutorials

Last edited by ragupasta : 09 September 2017 at 01:40 PM.
  09 September 2017
On a side note. Use render elements to troubleshoot possible areas. To to render elements and add the elements you wish to study. Do NOT enable them in the "Selected Element Parameters" as we want to study them in the VRay Frame Buffer (VFB). If you enable this, you need to set paths to write the images to disk.

Hit Render.

Then the top left of the VFB there is a drop down saying RGB Color. Change that to whatever you want to study. In this image I chose raw shadow. As you can see the white areas (ironically) are pretty noise free, apart from the very edges, but that is un-noticeable in the final render, so use these with caution. VRay will sometimes not fire samples into areas where is decides there is no need, so take into account that no all areas need samples.

My Houdini Tutorials
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