Render for C & C : trying new backdrop

[schultzeworks]

This is a new original design for a kitchen countertop organizer called "Vessella." I am trying a new backdrop and having trouble with the gradient; I'd like it to transition much more smoothly from light (@ floor) to dark (@ curved wall). Are there any tips to do this, besides just making it larger?

[schultzeworks]

Another idea

What if I move the backdrop closer to the model? That way, the lighting will spill on to the slope, but then fade with distance.

My goal is to get a more gradual white-floor to dark-backdrop gradient. The transition is too sharp right now.

[fpedrogo]

Re: Render for C & C : trying new backdrop

The main problem is that small top light is not enough to illuminate the background and that is why you have that dark area. In my opinion your background is to big, try to reduce the side of the background. If you don't want to change the size or the orientation of the lights, you should add other big rectangular light to illuminate the background. Big light in order to produce smooth shadow and also you can disable the affect reflection and specular in order to avoid that that new light affect the reflection on the model.

Best

[schultzeworks]

Great suggestion, getting better

Fernando : thanks very much for the feedback. I had already tried moving my backdrop closer to the scene (and it helped) but I will try making the light bigger / backdrop smaller as additional next steps.

QUESTION : I sometimes have a problem with noise in the shadows, as seen underneath the left-most organizer. What is the best way to correct for that? Image sampler noise threshold --or-- DMC sampler noise threshold --or-- material reflection subdivisions? I usually make the Image sampler and DMC sampler have the same noise values, around 0.002 for final quality. These tests are 0.01.

[Alexander Petrov]

Re: Render for C & C : trying new backdrop

Hi, just try to adjust light sampling subdivs from 8(default) to 16 or 32(but increase render time). If no change, than try to increase material subdivs!

[fpedrogo]

Re: Render for C & C : trying new backdrop

There many different noise in V-Ray, One is produced by the Irrandiance Map and usually is a big spotchiness on the wall and you can control these noise with the HSph. Subdivs under the Irr Map option. Other one is the noise produce by the antialiasing an usually are small grains on the wall specially on the dark areas and on the textures and you can controls these noise using the "Noise threshold" that is located under "Image Sampler" This option determine if the pixel needs more sampler, usually I don't use more that .005. There are other types of noise, for example the noise that produce the blurry materials. When you add highlight glossiness or reflection glossiness, that produce noise on that specific material and you can control that noise by increasing the subdivision on the material, the option is under the highlight and reflection glossiness. We have other type of noise that is produced by the lights, in this case by the two rectangular light that you are using and you can control he noise by increasing the subdivision of the lights. By default the subdivision for the light is 8 as Alexander said, try to increase that value to 16 or 32, those are the value that I use. Also I like to use my Irradiance Map calculation to calculate the effect of the rectangular light, so I enable "Store with Irradiance Map" this option also help you to avoid the noise on the shadows.

The other option to controls the noise is the "Noise Threshold" under DMC Sample, this option controls every single noise threshold option globally and the subdivs Mult. under the same rollout controls all of the subdivision in V-Ray. That mean that the DMC Sampler "Subdivs Mult. control the material subdivision, lights subdivision, Irr Map and Light Cache subdivision, etc. And more subdivision means more quality and more render time.\

In this case I believe that the noise is produced by the rectangular lights.


Best

[ozanb]

Re: Render for C & C : trying new backdrop

also if you place too much rectangular lights, lowering thresholds don't help much after a while
placing more than 3-4 area lights are troublesome in my experience

[fpedrogo]

Re: Render for C & C : trying new backdrop

placing more than 3-4 area lights are troublesome in my experience

You can use as many rectangular light you want, the problem are not the rectangular lights, the problem is the noise and subdivision setting. You have to know what is causing the noise to increase the correct setting and not kill your render time. For example some user tend to increase the HSph subdivision to much to avoid the splotshiness and maybe the that noise is produce for a poor Light cache solution. Again if you use store with Irrandiance map for the lights, the render is faster and with less noise.

Best

[schultzeworks]

New version

Thanks again for the excellent and detailed feedback. This latest version has solved the backdrop lighting problem quite nicely. I'm still planning to do more testing to address the noise issue -- and your advice will help a lot.

Depth of field blur tip: I found that the V_ray camera blur takes WAY TOO LONG to render, so I generated a Z-depth map instead. Inside Photoshop, you copy the Z-Depth into a channel. Then, you run the filter called filter-->blur-->lens blur and it's super easy. All you have to do is click on an area in the scene and that becomes your 'zone of focus.'

[ozanb]

Re: Render for C & C : trying new backdrop


6 rectangular lights, 5 with shadows and 12 subdivs, 1 omni, thresholds dmc and image sampler are 0.05 1280x571, dof 4 minutes 17 seconds
a smooth result but no shadow remains on ground

3 rectangular lights 1 omni, dof, 1 minute 58 seconds

schultze too much grey is in the background a white background would look better if you ask me

[schultzeworks]

Suggestions

Thanks for the tips.

1) The render time is not an issue, so the matte dinosaur file is not a good comparison. Its the transparent and translucent glossiness that Fernando alluded to. Plus, I have multiple 'layers' of clear, glossy, and shiny all stacked inside / behind each other.

2) I tried a white background, which I actually prefer. The problem is that the clear glossy material disappears into the same color background -- especially at the highlights / light reflections. You cannot tell what the design looks like, which is bad.

[ozanb]

Re: Render for C & C : trying new backdrop

dinosaur has reflection and glossiness yet no transparency, I may add transparency too

I understand what you mean, however your overall scene is too dark gray, try to solve the issue with material, not with background

[schultzeworks]

Update

This render has a few more material variations for a better composition. I also kept working on the backdrop, which was crazy-hard to get properly lit. The trick was to use a material over-ride of the GI, where I used a RGB=128,128,128 [neutral gray] to keep all of the scene GI off of the backdrop -- except for my two rectangular lights. Those lights were then easy to control how much spill hit the backdrop.

The last tip I will share is the backdrop render mesh. I cranked it up to the maximum (to be extra smooth) and then added more subdivs in the material reflection layer.

[ozanb]

Re: Update

I also kept working on the backdrop, which was crazy-hard to get properly lit. The trick was to use a material over-ride of the GI, where I used a RGB=128,128,128 [neutral gray] to keep all of the scene GI off of the backdrop -- except for my two rectangular lights. Those lights were then easy to control how much spill hit the backdrop.

I didn't understand this part, do you mean you just used a simple 128 gray material for background so that it didn't much effected by GI or anything else.

Metal reflections are great this time very sharp and crisp

for minor improvements, your site adress might lean right with same font size like previous image, green parts might use a slightly darker green with some bump like black parts, and slightly less glossiness or more subdivs for big transparent cup

thanks for the tips and sharing render, nice job

[schultzeworks]

Re: Update

I didn't understand this part, do you mean you just used a simple 128 gray material for background so that it didn't much effected by GI or anything else.

The gray is not a material color. Its a material GI color. Explanation:

The backdrop material has a GI override, activated within the material, so that the scene's Environmental GI lighting will not be used. You can find this material over-ride in the material editor, select the material, under maps tab, select GI, then use your own map or color. I used a 50% gray. That makes the GI lighting that does hit it appear even / flat / neutral -- so I can then position the rectangular lights to spill over exactly as I want.

The problem with the scene / environmental GI hitting the backdrop is that the backdrop is huge. It's then getting hit by your even huger 'dome of GI light' no matter what you do. I tried a million different material colors and reflectivity settings and nothing worked.