Using HDRI for lighting: trick I figured out today.

[simmsimaging]

I really like the ease of use that comes from using HDRI dome lights to create studio setups, but found that they are a bit limiting and always end up having to add at least a few extra lights or tweak them in Photoshop to merge a few, things like that, but figured out a good trick today that makes using them way easier.

I started out with a studio HDRI that has 3 lights (softboxes) and a black background. I split that out into 3 separate lights on black backgrounds (using Pshop). Now I have a top light, and two separate side-light spherical HDRI maps.

Then loaded them up one at a time into VrayHDRI maps, but put *those* into VrayCompTex maps, set to additive. Now I can place that in a VrayLight texture and I have HDRI softboxes that I can easily move around separately using the invididual image rotation controls. I can also add them on top of any generic background image I like using the same trick. Very easy to move them and each one can be adjusted separately for brightness and even colour (using other mix map types etc.).

If you need more lights just keep nesting more VrayCompTex inside of themselves and you have quite a few. So far I've only done 4, but that should cover a lot of bases already.

This might be one of those things everyone else is already doing, but it's new to me anyway and very handy so thought I'd share.

b

[sv]

that is a good idea...
Could I ask about the HDRI? Custom made or from a collection?

[tricky]

I find HDRI lighting tricky to get to grips with myself, particularly on exterior archvis shots. We have a couple of libraries, the main ones being from Dosche, but I always find it difficult to know what map type and what kind of multipliers I should be using to achieve a replacement for the vrayskylight that I typically use.

Vraysun + vraysky is fantastic, but I think using HDRs, particularly in the override reflection slot, would yield better results. I just find it difficult to get a result, run out of time and resort to using the vraysky option! Oh well. "My bad" as the americans would say.

[simmsimaging]

that is a good idea...
Could I ask about the HDRI? Custom made or from a collection?

Bit of both, but in this case they came from a purchased studio HDRI.

b

[voxel3d]

For exterior shots have you tried the HDR Lightprobes at http://gl.ict.usc.edu/skyprobes/

They cover a full day. They are not high res and you have to bring their exposure waaay down because they're incredibly bright, but they have full lighting range and produce nice shadows and highlights. The website says the full high res set is also available upon request though, i haven't asked for it. I've found they give a nice lighting quality and having the full day to choose from is great!

Jorge

[simmsimaging]

I find HDRI lighting tricky to get to grips with myself, particularly on exterior archvis shots. We have a couple of libraries, the main ones being from Dosche, but I always find it difficult to know what map type and what kind of multipliers I should be using to achieve a replacement for the vrayskylight that I typically use.

Vraysun + vraysky is fantastic, but I think using HDRs, particularly in the override reflection slot, would yield better results. I just find it difficult to get a result, run out of time and resort to using the vraysky option! Oh well. "My bad" as the americans would say.

Maybe give the "smart IBL" script and hdri's a try. I find they give a pretty good setup for a starting point.

http://www.hdrlabs.com/sibl/

I have not really had much trouble with HDRI's, but then again: I don't do arch-vis work, so I haven't experimented that much with lighting whole buildings this way.

b