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SGNLE

Unrealistic Lumen Output from IES Files

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Hello,

 

I am attempting to model some fixtures by a manufacturer using their IES files and finding that the light output in FQRW is highly unrealistic. Fixtures don't read at all until I manually set the lumen output to north of 2500 lumens (the environment being a very small office). The IES contained within has a lumen value of 261, which should read fine in a small environment.  I currently have the Emitter in Lighting Options set to around 1,400% based on another thread I looked at, but am hoping there is a way to get more lumen-realistic output with these fixtures set at 100% so that I can provide the manufacturer with renders that even somewhat realistically reflect the actual light output of his fixtures.

 

Any thoughts on how I can work these spotlight fixtures to create renders that are accurate to the actual details of the fixture/IES file and not just dialed in by eye? The biggest reason for this is that the manufacturer and I work remotely from each other and I don't always have the chance to use his new products in real life to get a visual sense of how bright they are in space and would love to rely on the data in the IES.

 

Thank You!

Office.vwx

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Maybe you can try changing the Camera Effects -> Exposure of the RW Camera to try and approximate more real-world lighting levels from .IES light fixtures.
 

I have never had much luck trying to match the expected IES lumen output in Vw without upping the Emitter as you read in that other thread. (Granted I haven’t revisited this topic in about 5 years, so maybe it’s been improved since). Perhaps @Dave Donley can weigh in on this thread.

 

If you need accurate photometric representation, you may need to use a more powerful (and much more complicated) third-party lighting package like Radiance

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Hello SGNLE:

 

As rDesign said, the brightness in the rendered image is relative to a virtual camera.  If you are feeding in physical values on the input side with the lights, then you also need to attach a physical camera on the receiving end.  To do this you use a RW Camera object, set it as the active camera (easiest using the Viz Palette) and turn on the exposure settings in the Obj Info palette Shape pane.

 

I tried this with your model and it is still pretty dim without overriding the IES brightness manually in the Shape pane.

 

Could you attach the IES file here?

 

Office IES Brightness v2022b210.vwx

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Hi Dave, 

 

It doesn't look like .ies file types are compatible with this board to post or message, and the file you attached won't open in my v2020. Is there another way I can send this to you?

 

Will look at the RW Camera today. Thanks!

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4 minutes ago, SGNLE said:

It doesn't look like .ies file types are compatible with this board to post or message

You can ZIP the .ies file first, and then it can be attached in a forum post.

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I noticed this post and downloaded the file. I can tell this model was mainly made in sketchup and brought into vwx. Watch out for the import settings, you have roof faces as vertical planes and that is strange to see. Regarding the IES light, in order to test it, I'd turn off all extra lights, no ambient, no backgrounds, etc. Then fast render and see effect. At 100% I noticed it vary dim with a blue tint to it. I don't think this light is that cold, kelvin should be lower, perhaps 2500k. 

The IES light should not be just in the middle of the room. It needs to be placed by the hanging lamp and the texture of the bulb set to glow, otherwise the scene does not look real.

To add more realism to this model,  there must be attention put on the textures, otherwise these look like dull wall paper. For example the tv texture must be set to glow and 10% reflection and other things like that. By the way, if you are going to create still renderings, make use of viewports and render at minimum 300dpi, using custom renderworks so you can have more control over what is needed and what is extra.


I am uploading the vwx file updated v2020 and a few screenshots.

IES 100 percent intensity.png

IES 150 percent intensity.png

Added lights.png

Only IES plus lamp.png

Office IES Brightness v2020.vwx

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3 minutes ago, Luis M Ruiz said:

...render at minimum 300dpi

 

This is highly dependent on viewport size (i.e. actual width/height).

 

I once saw someone setting up their renderings to fill a sheet layer page, and that page happened to be the same 24x36" size as their drafting plates. They were rendering at 300dpi and wondering why it took hours every single time! 😆

 

I typically use a 16"x9" viewport, and render at 120dpi for a Full HD image and 240dpi for a UHD (4k) image, but it depends on each person's output needs.

 

I also do test renders at a much lower DPI while I'm working, then increase only for final renders. Gotta save time somehow 🙂 

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DPI is dependent on the output.

 

If you're output is hard copy, then you only need 300 if you going to a comical print, like a book or a magazine. If the out put is going to be an inkjet print, then 125-150 is more than sufficient. Based on the size of the print. It is possible to get excellent results from around 100 DPI.

 

Most any service bureau use better, but printing technology similar to your home or office photo quality inkjet printer.

 

If your output is to a screen or projector nothing more than the resolution of the output device is wasted, so standard HD is 1920 by 1080 in pixel dimensions. If thinking 300 dpi, that's 6.4" by 3,6" with anything more wasted. Of course if the output deice is 4K, 5K or more, you do need more.

 

 

 

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4 hours ago, Dave Donley said:

I tried this with your model and it is still pretty dim without overriding the IES brightness manually in the Shape pane.

 

Could you attach the IES file here?

 

@Dave Donley would it make sense to use the IES info to make a spotlight lighting device?

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I don't think so, the main purpose is to get the interesting fringes and pattern of light from a complex fixture made out of reflectors and lenses.  Without calculating that from first principles.  With a lighting device I think you get a pretty smooth distribution without interesting fringes, if the device is good right?

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3 minutes ago, Dave Donley said:

the main purpose is to get the interesting fringes and pattern of light from a complex fixture made out of reflectors and lenses

 

I've not actually tried using an IES file as a basis or a Spotlight Lighting Device. It is something I have considered, less for rendering, but more for using the photometric tools and measuring output.

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13 minutes ago, Kevin Allen said:

 

I've not actually tried using an IES file as a basis or a Spotlight Lighting Device. It is something I have considered, less for rendering, but more for using the photometric tools and measuring output.

I don’t believe that .IES lights will work with the Spotlight Photometric grid.

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24 minutes ago, rDesign said:

I don’t believe that .IES lights will work with the Spotlight Photometric grid.

 

On their own, they will not, But I have considered gathering the data and entering into the LIR for use with the photometric tools. This is something I haven't tried, I usually want the glints an IES file adds to a render

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