light gels anyone

Francois · September 23rd, 2003

Hi. Has anyone tried this?

Is it possible in LS to use light gels ( a transparent surface with a bitmap on it) the way they create certain moods in theatres.

The light goes thrue the ''filter'' and projects the images on the scene.

Thanks in advance.

Arnold Gallardo · September 23rd, 2003

Hi,

Actually it depends on how much fidelity you want. To me those 'illuminated posters' are noting but diffuse light sources so it should be possible if you have the proper candela or lux level designations however having said that LVS will not be able to do nor simulate light transmission and dispersion effects. As you probbly know radiosty does not account for these kinds of light transfer.

If all you care is to simulate the ambience that these displays give then I'd just designate the polyface to either be an area light source or designate it throgh its material properties with 'Luminance (glow)'.

I hope this helps.

Francois · September 23rd, 2003

Hi. Thanks for the quick reply.

It is not exactly what I had in mind. You are explaining the concept of lightboxes, like we see a lot in store displays.

What I was hoping to do is more like the effect of a projector of a movie theatre. The ''gel'' is small and place in front of the light source, to project the image across the room on a floor or a wall. Any hints how to do it?

Thanks

Ernest Burden · September 23rd, 2003

Quote:

What I was hoping to do is more like the effect of a projector of a movie theatre. The ''gel'' is small and place in front of the light source, to project the image across the room on a floor or a wall.

Have you tried placing a material with a bitmap on it set to 'blend', color white, with the material transparency set to 100% and the light source set to raytrace direct? Well, have you?

Francois · September 24th, 2003

Hi Ernest. I've tried with different transparencies with bitmaps, but not with blend. raytrace direct ON.

I remember once, it worked ( unwanted effect) when I place a background plane with an image, It was an interior shot with raytrace sunlight.

I want to do it for a theatre scene.

Thanks.

Arnold Gallardo · September 24th, 2003

Hi,

Sorry for the confusion. Anyhow what you are trying to do can be done using good old 'projector light' which uses texture maps as image sources and needs raytracing to work although some render engines can also do this using shadow maps.

I have not tried to do this in LVS but I know I can do this in an .LS imported into LW 5.6. That might be your only path if you do actually need this done. In any case you can always do a composite image.

Ernest Burden · September 24th, 2003

Quote:

I remember once, it worked ( unwanted effect) when I place a background plane with an image, It was an interior shot with raytrace sunlight.

I have only tried this effect with sunlight, but it worked as expected, subject to meshing parameters on recieving surfaces, of course, since the projected image will be treated as a 'shadow'.

Arnold Gallardo · September 25th, 2003

Yeah but I think he wants a sharp image not a blurry patchwork although I doubt higher meshing resoutions would have helped although I have not specifically tested to do this. HEY! maybe my intimate knowledge of radiosity is curtailing me..

I better change

Francois · September 25th, 2003

Wow, thanks every one.

I've been a bit busy today, I haven't had time to test it yet. I'll keep you informed and post some images. I do not need a sharp crisp image, I just want to set a mood with color and lighting. Like they do in theatre design.

Thanks

September 23rd, 2003	#2 (permalink)
Arnold Gallardo Senior Member Join Date: May 2002 Location: New York Posts: 225 Name: Arnold Gallardo	Hi, Actually it depends on how much fidelity you want. To me those 'illuminated posters' are noting but diffuse light sources so it should be possible if you have the proper candela or lux level designations however having said that LVS will not be able to do nor simulate light transmission and dispersion effects. As you probbly know radiosty does not account for these kinds of light transfer. If all you care is to simulate the ambience that these displays give then I'd just designate the polyface to either be an area light source or designate it throgh its material properties with 'Luminance (glow)'. I hope this helps. __________________ _ _ ______________ _ _ Arnold Gallardo Visual Content Creator Technical Writer Author:'3D Lighting: History,Concepts and Techniques'

September 24th, 2003	#6 (permalink)
Arnold Gallardo Senior Member Join Date: May 2002 Location: New York Posts: 225 Name: Arnold Gallardo	Hi, Sorry for the confusion. Anyhow what you are trying to do can be done using good old 'projector light' which uses texture maps as image sources and needs raytracing to work although some render engines can also do this using shadow maps. I have not tried to do this in LVS but I know I can do this in an .LS imported into LW 5.6. That might be your only path if you do actually need this done. In any case you can always do a composite image. __________________ _ _ ______________ _ _ Arnold Gallardo Visual Content Creator Technical Writer Author:'3D Lighting: History,Concepts and Techniques'

September 25th, 2003	#8 (permalink)
Arnold Gallardo Senior Member Join Date: May 2002 Location: New York Posts: 225 Name: Arnold Gallardo	Yeah but I think he wants a sharp image not a blurry patchwork although I doubt higher meshing resoutions would have helped although I have not specifically tested to do this. HEY! maybe my intimate knowledge of radiosity is curtailing me.. I better change __________________ _ _ ______________ _ _ Arnold Gallardo Visual Content Creator Technical Writer Author:'3D Lighting: History,Concepts and Techniques'

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September 23rd, 2003	#1 (permalink)
Francois Member Join Date: Oct 2001 Location: Piedmont, Quebec Canada Posts: 60 Name: Francois Letourneau	Hi. Has anyone tried this? Is it possible in LS to use light gels ( a transparent surface with a bitmap on it) the way they create certain moods in theatres. The light goes thrue the ''filter'' and projects the images on the scene. Thanks in advance.

September 23rd, 2003	#3 (permalink)
Francois Member Join Date: Oct 2001 Location: Piedmont, Quebec Canada Posts: 60 Name: Francois Letourneau	Hi. Thanks for the quick reply. It is not exactly what I had in mind. You are explaining the concept of lightboxes, like we see a lot in store displays. What I was hoping to do is more like the effect of a projector of a movie theatre. The ''gel'' is small and place in front of the light source, to project the image across the room on a floor or a wall. Any hints how to do it? Thanks

September 24th, 2003	#5 (permalink)
Francois Member Join Date: Oct 2001 Location: Piedmont, Quebec Canada Posts: 60 Name: Francois Letourneau	Hi Ernest. I've tried with different transparencies with bitmaps, but not with blend. raytrace direct ON. I remember once, it worked ( unwanted effect) when I place a background plane with an image, It was an interior shot with raytrace sunlight. I want to do it for a theatre scene. Thanks.

September 25th, 2003	#9 (permalink)
Francois Member Join Date: Oct 2001 Location: Piedmont, Quebec Canada Posts: 60 Name: Francois Letourneau	Wow, thanks every one. I've been a bit busy today, I haven't had time to test it yet. I'll keep you informed and post some images. I do not need a sharp crisp image, I just want to set a mood with color and lighting. Like they do in theatre design. Thanks

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