directional area light

[jon3de]

Hi, 

This is an area light with directional parameter turned on in vray. 

What would be the best way to achieve this type of light with mantra. The spot parameter on the grid light is not giving me the desired results for now. Thank you. 

Jon

[davpe]

I'm afraid if spot light parameters are not giving you what you want it would be best to just juse a gemetry to block the light if you know what i mean. just make a wall with a hole in it and put the light behind it.

[jon3de]

Hey David, Yea Thank you. I could do it like that but i think its way harder for the renderer to calculate it and dependend on the scene not always so easy to setup. Also SideFX pointed out that I can use a spot light in combination with a texture what kind of gives me some good results. In production so far it was nice to have a parameter that controls just the light distribution of an area light and the shadows etc. change accordingly. I thought maybe there is something in houdini lights and I just dont know about it. 

directionalLight_example.mp4

[davpe]

hi yeah texture is also a valid way how to approach it. performance-wise it will be much less efficient than using geometry blocking (sampling noise). I think using geo blocking doesn't actually add anything to the render time (why would it?). currently there are no other options out of the box for driving "directionality" of area light sources, other than already mentioned. of course if you are resourcefull enough you can build your own light shader. that's one of awesome things about Mantra that it's so open to allow you to do that. me, in most cases, can get the job done with spot light sliders or geo blocking, (or maybe using multiple parented lights) , and light texture being the last resort in some special cases. very much depends what the scale of your scene is - for small scenes using textured lights can be perfectly fine, with larger scenes less so. cheers.

[jon3de]

hey, I thought because of the sampling I need higher render settings and this will lead to higher render times. But maybe I was wrong here. I tried it with some geometry as a light blocker and linked it to only this light - it works better that expected  Also the hint with the light shader ist interesting  ( although behind my skills yet ) I will have a look into that. Thanks David.