area light scaling and U/V size

V-Ray V-Ray for Maya General
1

Hi,

In Vray 3.6 and going forward, is it safe approach to simply scale a rect light’s ScaleX and ScaleY instead of changing the U Size/V Size?

I did a quick test. It seems that a Rect light of ScaleX 3 and ScaleY 4 is lighting a sphere is equal to a Rect light of U Size 3 and V Size 4. But I would like to hear with other users experience and maybe a confirmation from devs.

Thanks,
Jason

2

There shouldn’t be any issues except that you can get confused with the managing of the lights size in the scene.

3

Thanks, Zdravko. So there is no negative effect on render time or sampling if I adjust Rect Light size through Maya’s scaling instead of the light’s U/V Size. In terms of getting confused about managing lights size in the scene, if I am consistent on how lights size is controlled, then that can be avoided, right?

4

Yes, there shouldn’t be any negative effect on the render time or sampling. As long as you stick to one way of resizing, to avoid confusion, you will be fine.

5

Thanks so much for the confirmation, Zdravko.

6

That being the case, it would be good to see the UV attributes removed from the light.

7

I’m not sure since this is the official way of operating and a lot of artists are still using it. But we will consider your suggestion.

8

hi, in the latest version, im getting differences in the viewport with an area light where 1 is scaled with maya transforms, the other with vray U and V. (so they should be identical) Is this a bug? I’ve attached a scene.
arealight.rar (12.2 KB)

9

No. The correct way to change a light’s size is to change the U/V attribute values. While scaling might work better now, it is certainly not something I would recommend as an everyday workflow.

Best regards,
Vlado

10

Hey Vlado, I got a bit confused now. I have not preference in terms of removing U/V attribute from UI. If scaling might work better now and Zdravko said there is no negative effect on render time or sampling, why wouldn’t you recommend to adjust rect light size by scaling?

11

Non-uniform scaling allows you to get light shapes that we don’t support (e.g. skewed lights, or ellipsoids) and this could lead to confusion and incorrect results. Stcking to the size attributes is always predictable. Also using physical light units like lumen assumes that lights are not scaled.

Ovbiously uniform scaling needs to work for the cases when a model is scaled up or down, but if you just need to change the light dimensions, the attributes are preferred.

Best regards,
Vlado

12

@vlado Thanks for the explanation. Too bad there seems no intuitive way to adjust u/v size in Maya viewport. I feel it’s not intuitive to resort to attributes editor to adjust light dimensions which takes users focus out of viewport and lost the context of scene. My eyeballs are constantly moving back and forth between viewport and attribute editor to check the light dimensions. That’s probably part of the reason people tend to adjust light dimensions by scaling in viewport.

I remember in Katana, users can drag area light edges to adjust u/v size directly in its viewport. How likely is to add that kind of control for Maya if you deem that useful?