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Beam Angle 2 and Field Angle 2

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When I adjust the 2nd Beam Angle of a lighting instrument, the beam is drawn correctly (as an ellipse) but the rendered light of the primary beam angle is the only one shown.

I'm trying to make a custom instrument that is actually a 3-foot by 3-inch LED wash fixture. An ellipse pattern throw would help me simulate its performance.

What exactly is the purpose of the Beam Angle 2 and Field Angle 2 if they won't render?

See attached image.

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Thanks. Unfortunately this type of instrument cannot be created in Vectorworks yet, no matter what the IES data says. Vectorworks only uses a single point source for lighting instruments.

Here is a picture of a Colorblaze 72 from the Vectorworks library. In reality the source is 6-feet wide. But as you can see, the result is nowhere near what the actual beam of a Colorblaze would be.

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Just to be clear: It cannot be created with a spotlight instrument.

It can be created (more or less) with one or multiple generic light objects using IES data.

With instruments like the colorblaze 72 there's no way to accurately model the light output using the light built into the instrument.

You can fake it w/ the IES data - if it's available. I've sometimes used area lights. The result is never great.



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2 questions. So we have hundreds of instruments in the Spotlight Entertainment library, every brand and model you can name, but they don't have IES data for anything that doesn't put out a round beam? The instruments in the attached screenshot are a Sellu64, 36 degree S4, and a varilite. Are you saying I can do something with the data on the Selador to get it to render more accurately?

Also, could someone share the steps on importing IES data. So far I can't find instructions on that.

Thanks for your feedback Michael.

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There is no .ies data for any instrument in the library.

My understanding of this is probably wrong (Kevin? :) ) but this is the jist of it:

1. Draw Beam creates a cone each for field angle and beam angle. I think it used to be just one angle. i.e., the beam had to be a circle. Don't remember when the second angle was added to get an oval for PARs.

2. The photometric calculations are just that: calculations. It uses the initial output of the fixture and the inverse square law and (I believe) some factor of an arc tangent to calculate falloff to create the foot candle grids. It doesn't actually use a light object for photometric calculations. Drawing a wall between the light and the stage will not change the photometric grid!

3. Baked into the secret sauce of the Spotlight Lighting Device is a generic light object. To make it more confusing, it's called a Spot Light. It has the correct beam and field angles. But I believe the fall off is set to "None" by default. That lighting object can only create a simple round beam of light.

To create a light object w/ IES data:

First - I've found that not all IES files are created equal. An ies file is nothing but a space delimited ascii file with a bunch of numbers (you can open them with a text editor). The GE file for the 1k PAR 64 WFL lamp has 10 short lines of data. The file for the street light fixture in the example has 120 long lines of data.

1. Download the ies file from the manufacturers website.

2. In VW: Visualization Tool Palette > Light Tool > Custom Light Mode > Click to place in drawing. If it's the first custom light in the drawing it will ask you for the Load Distribution.... Navigate to the .ies file you downloaded.

You can change the ies file from the OIP, or specify the file to be used for subsequent light objects in light preferences.

Example attached.



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Thanks for your time. I've been wrestling with this from time to time for over a year. I'll play around with some IES data.

Currently I have a 3-foot wash unit hanging behind a ceiling beam, on a 38 degree tilt. (There is no room to change the focus of this instrument. It will have a straight shot) Yes, I can draw the instrument and draw my 15 deg. beam spread and all that. But it would be so much easier to place the instrument, turn it on, and show the director and lighting designer the light spill on the set walls.

This has worked with all the Source 4 instruments. If the lighting designer wants a specific shot, we could do it the old fashioned way and plan the shot with a section view and plan view. But its so nice to see the shot by hanging the instrument above the model, turning it on and rendering it. And then I blow them away further by inserting the exact gobo and gel color they want.

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  • Vectorworks, Inc Employee

There are a few symbols in Vectorworks that use .ies files but as you have seen the quality and more importantly for us the orientation represented by the .ies file can vary greatly.

The Draw Beam options use the Beam Angle and Beam Angle 2 fields but the actual rendered light is round because the Spot Light can only produce a round beam, you need a custom light to produce anything but a round light. You can edit the Light in the Lighting Device, change the type and supply and .ies file then orient and map the .ies file.

In the future we would like to utilize the existing data to automatically produce a pseudo .ies file that would draw an oval beam for the lighting device.

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