Can the Photogrid work with a Custom Light.

[bcd]

Hi,

I'm creating a custom light using a client supplied .ies file.

All good.

I'm creating a symbol from said light and converting to a lighting instrument.

Then I insert the lighting instrument and focus it to a focus point.

Draw beam: selected

Create a photo-grid that falls within the beam.

But - the grid doesn't report any values.

However - if i select a pre-cooked lighting instrument from the Instrument Symbol library file and focus it - draw its beam then the photo-grid duly reports the illumination values.

I'd like to be wrong but could it be that a custom light using a distribution file can never interact with the photo-grid.

Apologies if this has been answered already.

Thanks for any input.

B

[michaelk]

You are correct. The photo grid tool works w/ spotlight instruments ONLY.

It calculates light from each instrument using the beam and field angles and inverse square law along the focus vector. (and an arccosine function for the falloff.)

It is a calculated value. If you put a brick wall between the light and the focus point, the foot candle value remains unchanged.

The light object w/ the ies data will render correctly, but the light level can't be calculated in VW.

This has been a frequent wish list item.

michaelk

[bcd]

Thanks Michaelk,

How do we trick VW into thinking my instrument is a VW spotlight instrument

or is there a way to modify a VW Spotlight instrument to approximate my custom light?

It makes sense that calculating reflected & ambient light / texture effects is intricate ("orders of magnitude more complex") but calculating direct light from a distribution file should be relatively simple, no?

[michaelk]

I think you have to fake it.

You can have a Spotlight instrument symbol w/ all the data and label legend yada yada.

Then place the light object w/ the ies data in the same place as the instrument and focused where you want it. Put the light object in it's own class. Turning that class from visible to invisible will act like a light switch for rendering

If you want the footcandles, you only need to enter the correct beam and field angles and candlepower in the symbol definition.

This only works for directional light fixtures. If you have the IES data for a fluorescent tube, for example, I don't think there is a way for Spotlight to calculate the footcandles.

hth

michaelk

[michaelk]

This might make more sense...

Attached is a nonsensical example. The light object has the .ies file from a random parking lot light fixture. The instrument has made up data. It should be data from the actual fixture.

In the Vis. Pallet try turning off the light that's on and then make the class "IES Light Object" visible. The ies light object will render and appear in the Vis palette.

The photo grid will only respond to the light from the spotlight fixture.

hth

michaelk

[bcd]

Yes, this makes sense.

What doesn't though is:

Taking your example.

Convert ies light to a symbol.

Converte symbol to instrument.

Focus to focus point.

Draw beam.

Photogrid doesn't respond (when Calculating using visible beams)

even when I input wattage, color, angle & falloff fields as the Spotlight fixture.

What I don't understand is what component does the Spotlight have that our custom lighting instrument is missing to enable it to speak to the photgrid.

I do notice that the RB is populated with 2 symbols every time I import a SL instrument, perhaps there's a clue there.

again thanks M for your input. If it can't be done then so be it, but it's very puzzling, no?

[michaelk]

You can not get the ies light into an instrument. (unless someone else has a way)

Instruments (to my shaky and uncertain knowledge) can only use the data in the record attached to the symbol. That data can only be initial intensity, beam angle, and field angle. Not IES.

The Photo Grid can only read information from instruments. So it will never read any light from IES data.

There are two separate lights in this example:

1. Spotlight instrument - uses data from record, works w/ photo grid, etc, renders light to match data

2. Generic Light Object w/ IES data - renders accurately - doesn't work w/ photo grid- can't be part of spotlight instrument

To the best of my knowledge, you can't combine the two.

In the taco example you could render the IES data and come close to approximating the beam w/ the spotlight symbol and calculate footcandles, if you knew the photometrics. I think that's as close as we can get...

hth

michaelk

[michaelk]

The reason that the RB has 2 instruments is that most symbols nest a symbol inside them.

For example the ETC Source Four 19? uses it's own 2D part, but for the 3D part it uses a symbol called S4 body (or something like that). All the S4 ellipsoidals can use the same nested 3D symbol.

I think most or all of those symbols have "body" in the name. They have no records attached. They're just symbols.

hth

michaelk

[Horst M.]

Hi,

If I have to do all this Photometric Calcualtions, for Architectural Lighting Projects,

I use DIALux to do the calculations and the Paperwork.

The Software works with .ies .ldt and other Lighing Data Files supplied by the manufacturers of Architectural Lighting Fixtures.

The Workflow to do do the Construction of the Space with VW, export the Projekt as .dwg, and import the Projekt to DIALux works fine (for me).

And DIALux Is made for these Kind of Calculations, and it's free.

I know this is not exactly whats discussed in this thread, but may be it is a good workarround for the Problem.

Edited April 10, 2010 by Horst M.

[michaelk]

Horst

Is there a Mac version, or are you running it in Windows?

[Horst M.]

It's only available for windows.

I've installed it on the Autocad PC in the Office.