Photometric IES light issue

[bobmsn]

hi, I'm using a photometric IES light and each time it renders I get the same effect, in that the beam seems to 'slice' off.

 

this only applies in the down beam, and I have tried different IES lights, a different wall, different wall textures, isolated the wall and the light - literally everything, even down to remaking everything concerned and changing the camera angle, yet I still cannot fathom out the problem.

 

if anyone could shed some light on this (pardon the pun) I would be highly greatful.

 

thanks, bob

[YOHKOH]

At the risk of sounding obvious but have you tried removing the light fitting geometry and rendering.

 

I find problems if I have any geometry too clost to the light.

 

If the light are right up against the wall or tight up against the fitting.

[bobmsn]

hi, thanks for your swift reply.

 

the lights are below the case, but even when I've rendered with the lights on their own the problem still occurs.

[mattclinch]

what does your wall geometry looks like?

[YOHKOH]

Hi I just tried copying a similar setup to yours.

 

I'm using vray btw.

 

Rubbish results with IES, as soon as I get the light shade anywhere near, it all goes wrong.

 

Conclusion, I dont know whats going on.

[bobmsn]

my wall is flat.

 

thank you for taking the time to do a test.

is the conclusion that ies lights are rubbish then?

[bobmsn]

...and yes, I am using vray as well.

[Peter M. Gruhn]

I did a quick test and found what I always do with photometrics... I like them and get good results. I use vendor supplied IES if I can find out what's spec'ed for the project. No worries. Scanline or Mental. Near a wall or far away or sticking through so it shines on both sides. Rotated or not. I can not think of a way to duplicate your issue.

[luckymutt]

Can you post the IES file? or even the scene?

I haven't seen this before.

I agree with Peter. I've never had an issue. In fact, I have never seen anything to suggest that IES lights are "rubbish." Although most of my work (photometrically) has been done with mental ray and scanline with no problems. I wonder if it is a VRay issue.

I have access to VRay at work, so I'd like to give your file a shot across several render engines.

[Stephen Thomas]

Are you using camera correction? If so make sure you have disabled 'Use MAX-compatible ShadeContext' in your render settings.

[bobmsn]

Stephen Thomas - you sir are a genius. thank you so much.

 

I had not even seen that tick box before let alone have a clue what it does.

 

if that is all it does then it's a worthwhile addition!

but thanks to everyone that took the time to help.

Edited February 11, 2010 by bobmsn

[Stephen Thomas]

No probs, I only know through having been in exactly the same situation myself - http://forums.cgarchitect.com/27459-uplighter-problem.html

 

I even used the same pun!