Render Dialogue Query

[dj_buckley]

In the standard render dialogue under the statistics section it tells you the number of Objects/Faces etc.  It also has a number for 'lights' - i'm just wondering what this number is telling me?  On my current scene it says Lights = 4975.

The scene is an exterior lit purely by and HDRI, so I'm just wondering what that 4975 is?

[dj_buckley]

Attached a screenshot to show what I mean - in this scene there are no grouped objects and only 1 plane light and an hydra in the environment

[pokoy]

Geometry lights with LightMtl count as lights, the first number are individual faces, second number is the internal number of how Corona handles them.
You probably have geometry lights in the scene, if not either light handling changed or it's a case for a dev investigation.

[PROH]

Hi dj_buckley. Just to clear things up: Are you talking about two different scenes. One with a spherical HDRI, and one with a plane light + hydra? (What is "hydra"?)

Edit: just tested it (Corona v1.7)
- A scene lit only by a spherical HDRI gives 1(1) = 1 light in 1 group
- A scene lit by a spherical HDRI + 1 Corona rectangular (plane) light gives 3(2) -> 3 lights in 2 groups.

Are you using LightMtl or some sort of VRay lights?

[dj_buckley]

sorry nope it's the same scene, 1 plane light, 1 hdri in the environment slot (my macbook autocorrected to Hydra without me noticing).

There are a couple of light materials, 2 unique light materials.  Definitely nowhere near 5000

[PROH]

Hi. Posted an edit at the same time you wrote. Please read it :)

So I guess you're having 10 objects with around 5000 faces using LightMtl?

[dj_buckley]

I've seen it, there are definitely no hidden lights, no vray lights, just an environment hdri and a plane light, and a couple of light materials.

But nowhere near 5000.

[dj_buckley]

So i just found some light materials that were being used on stock models and it's now dropped to 93.  Still way more than there is, and I still don't understand the numbers.  For example, in your test, why did it say 3 lights in the scene that only had a plane and hdri?

[PROH]

HDRI counts a 1 and a rectangle/plane has 2 faces and therefore counts as 2 lights in 1 group. So if you're using a mesh with 500 faces (tris) with LightMtl, then it will be counted as 500 lights in 1 group.

[dj_buckley]

Ok good to know - and would that affect rendertime? i.e. would a light material on a plane with 10 faces, render longer than a light material on a plan with 2 faces?

[PROH]

I think yes, but I doubt the difference between 2 and 10 faces will be noticeable. The difference would be bigger if it was between 2 and 10 light groups.

Anyway, I think this could be explained more exact by Ondra or some other dev :)

[dj_buckley]

Hmm interesting - well this appears to be the difference between 100 and 5000 lights so it's quite possible adversely effecting my rendertimes.  I had light materials on a high poly car headlamp etc

[dj_buckley]

Just deleted all of my light materials (went through every material) and it's back down to 3(2).

[TomG]

BTW in 1.7, there are tooltips for all the stats like Geometry Groups, Lights (groups) etc. just in case you want a description of what the numbers are showing.