Simulate linear array of multiple LED light sources?

[GilesPhillips]

With the massive increase in LED lighting I'm suprised this hasn't come up sooner..

We're working on visualising an external lighting scene which uses light fittings that consist of a line of high intensity tri-colour LED lights with a variety of pre-set lens/beam patterns.

typical light source: Pulsar ChromaPowerLine

The problem I'm having is simulating this effect in a semi-accurate way, without making a massive file full of light sources.

Using a photometric light, the typical light distribution is as if from a point, even if the 'emit light from (shape) option/parameter is set. I'm looking to create a 'curtain' of light rather than a 'fountain'. I could use an array of single light sources placed closely together, however I think I'd end up with thousands of light sources given the size of the building (it's a high-rise)

has anyone else had this problem? got a solution?

G

[GilesPhillips]

With the massive increase in LED lighting I'm suprised this hasn't come up sooner..

We're working on visualising an external lighting scene which uses light fittings that consist of a line of high intensity tri-colour LED lights with a variety of pre-set lens/beam patterns.

typical light source: Pulsar ChromaPowerLine

The problem I'm having is simulating this effect in a semi-accurate way, without making a massive file full of light sources.

Using a photometric light, the typical light distribution is as if from a point, even if the 'emit light from (shape) option/parameter is set. I'm looking to create a 'curtain' of light rather than a 'fountain'. I could use an array of single light sources placed closely together, however I think I'd end up with thousands of light sources given the size of the building (it's a high-rise)

has anyone else had this problem? got a solution?

G

[Steve_Curley]

It has been done before (back in 2009) but it did use an array of lights so it may not be suitable in this case. All I can remember about it is that it was based on an image sequence (essentially a movie), it created the lights (1 light per pixel in the images, IIRC) then read the imagelist and created keys in the color values to animate them correctly. The script is attached if you'd like to play with it.

ledcreatev2.ms.zip

[Steve_Curley]

It has been done before (back in 2009) but it did use an array of lights so it may not be suitable in this case. All I can remember about it is that it was based on an image sequence (essentially a movie), it created the lights (1 light per pixel in the images, IIRC) then read the imagelist and created keys in the color values to animate them correctly. The script is attached if you'd like to play with it.

ledcreatev2.ms.zip

[GilesPhillips]

I want to try and avoid the multiple sources per fixture approach if possible. The quantity of fixtures is going to make this an impossible task. There's nearly 300m of edges that need to be lit with these fixtures, and each fixture has a LED pitch of 25mm, so that would make a worst case scenario of over 11000 light sources!

Part of the problem is that max doesn't really ackowledge the shape of the light source, it treats all spot light sources as point, regardless of the 'Emit light from (shape)' setting.

I've tried experimenting with other approaches simulating a 1200mm fitting (which should contain 48 LEDS), from left to right in the attached image:

1) Omni source in a shaped enclosure - falloff is wrong and calculating proper light output will be difficult.
2) Photometric source with IES file from supplier - falloff appears better right but distribution is as if from a point source.
3) Multiple (48) sources using IES file - falloff appears right and distribution is believable however it's going to push the qantity of lights (and rendering time) into the stupid realm.
4) Multiple (12) sources using IES files - probably an acceptable minimum to the multiple sources (4x less than reality) which doesn't screw up the light distribution too much

Obviously when this lot is seen in context things may change, but for the time being, can anyone make any other suggestions?

[GilesPhillips]

I want to try and avoid the multiple sources per fixture approach if possible. The quantity of fixtures is going to make this an impossible task. There's nearly 300m of edges that need to be lit with these fixtures, and each fixture has a LED pitch of 25mm, so that would make a worst case scenario of over 11000 light sources!

Part of the problem is that max doesn't really ackowledge the shape of the light source, it treats all spot light sources as point, regardless of the 'Emit light from (shape)' setting.

I've tried experimenting with other approaches simulating a 1200mm fitting (which should contain 48 LEDS), from left to right in the attached image:

1) Omni source in a shaped enclosure - falloff is wrong and calculating proper light output will be difficult.
2) Photometric source with IES file from supplier - falloff appears better right but distribution is as if from a point source.
3) Multiple (48) sources using IES file - falloff appears right and distribution is believable however it's going to push the qantity of lights (and rendering time) into the stupid realm.
4) Multiple (12) sources using IES files - probably an acceptable minimum to the multiple sources (4x less than reality) which doesn't screw up the light distribution too much

Obviously when this lot is seen in context things may change, but for the time being, can anyone make any other suggestions?

[Anonymous]

IES lights are always seen as Point lights, as you found.

Iray doesn't care how many lights you have; if you do a lot of these then that may be something to consider. We routinely model every LED for projects, and have upwards of 2000 lights in a scene. 

For the cost of an NVIDIA Titan card or three, you can burn through images fairly fast.

[Anonymous]

IES lights are always seen as Point lights, as you found.

Iray doesn't care how many lights you have; if you do a lot of these then that may be something to consider. We routinely model every LED for projects, and have upwards of 2000 lights in a scene. 

For the cost of an NVIDIA Titan card or three, you can burn through images fairly fast.