DOF at large scale

[Bruce Hart]

The other day I saw a block architectural model on here rendered to look like a physical model with wood materials and DOF. Looked cool. I've had a go at this look in the past many times also. I can get DOF working no trouble on objects at a small scale (actual model size), but I always have difficulty getting the DOF to work on a large building scale scene. It can work with a very small F Stop and high shutter speed, but can be very grainy as you would expect.

What do I have to do to make a Physical cam with exposure, produce DOF on an actual size building to make it look like a small scale model? I was thinking you needed to adjust the Aperture size to some large amount under the VRay:: Camera rollout with "Get from camera" option unticked - but this never seems to work for me. My units are cm with m display.

Sorry for this dumb question, but just humour me

[vlado]

You'll have to scale up the film gate and lens focal length parameters.

Best regards,
Vlado

[Neilg]

Adjust your lighting so it's the same as with exposure off and you can use a standard camera which is much easier. You get a viewport preview so it cuts out any trial & error.

Switch it on in the standard camera, do a preview, then keep raising the 'sample radius' until it looks exactly how you want it. Then turn DOF off, and switch it on in the vray settings. Whatever your sample radius was, drop that into the 'aperture' box.

[Bruce Hart]

Thanks guys - I'll give it another go.

....OK I tried again, this time using RT GPU for feedback - worked very well. I had tried scaling the Film gate/Focal Length before, but just went a bit too low with the F-Stop. This time I also lowered the ISO a lot to counter the grain. Got it now

My goal was to not lower the lighting level, but just alter the camera settings. I'm actually inspired to use RT more in my day-to-day workflow. Thanks again.