Inconsistent lighting fixture render

[steve]

Hello all:

I am using the identical recessed can lighting fixture in two different models. In short, the fixture renders correctly ('illuminated' and throws light) in one model, but not the other. The render settings of the two models are identical, and the lights are turned 'on' as part of that setting for both.

A basic draft mode render or a cloud render yields that same confusing and frustrating result. How is this possible?

Any help is appreciated!

[ToanDN]

Relax and take your time. I am cooking.

[steve]

Pardon my ignorant question, but I don't understand this "blocking" thing?

Further, if the family works in one model, but not the other, I don't understand what that has to do with the family?

[barthbradley]

@steve: it has to do with Materials. Something translucent in one project, is not translucent in another.

...transfer Project Standards: Material Definitions from "good" project to "bad" project and see results. 

[steve]

Sorry, I don't follow "delete everything but the Ceiling Opening and the Light Source"?

[barthbradley]

@steve: the light source is surrounding by geometry. That geometry's material transparency is different in one project from the other. Get it? Just do as I said and delete everything but the Ceiling Opening and the Light Source from the family and reload it and re-render it. Does it render well or no? 

[steve]

Transfer 'Materials' or 'Materials Definitions' (I don't see the later, only the former)?

[steve]

Yes, I think so.

[barthbradley]

Transfer Project Standards

[barthbradley]

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@Anonymous wrote:

Yes, I think so.

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Okay...does that correct it for you? 

...deleting everything in the family was just a trouble-shooting step. It appears the materials are the blame. Leave the family intact, and use Transfer Project Standards to transfer the material definitions from the "Good" project to the "Bad" project  -- overwriting when prompted. Should solve the problem. No?

[steve]

Nope.

😞

[barthbradley]

@steve, buddy, pal...what do you mean by "nope". Nope what? 

[steve]

It did not solve the problem.

[barthbradley]

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@Anonymous wrote:

It did not solve the problem.

---

What's "IT"? 

[steve]

Transferring the materials did not solve the problem.

[Anonymous · Accepted solution]

Your light is inside the fixture geometry.

Move the light outside of the fixture geometry. You will need to "unlock" the light in Elevation view.

Doing the light section I proposed earlier woul'dve highlighted this common problem.

Since most lights are terribly modeled, I would encourage you not to play with lighting until you are comfortable making your own light families. Lights are some of the most misunderstood families in Revit and 98% of light fixture models are garbage (wrong lumen value, wrong light type, wrong light location, wrong materials, wrong Light Loss Factor, etc).

You best bet otherwise, is to find some of the few lighting manufacturers that provide accurate Revit light families, but they are few and far in between.

PS, if you want more light, adjust the "initial intensity".

[steve · Accepted solution]

Okay, so I discovered a "work around" late last night (purely by luck) that solved the problem I've been having.

@Anonymous is correct (sort of ... I think ... yes?) about moving the light source. I tried his suggestion, and it did cause light to emit from (and appear to illuminate) the light fixture, but the result was kind of harsh looking. Disclaimer: I'm assuming I did it correctly.

The project I'm using this in is a residence, with a GWB ceiling placed snug up against a framed floor system. So the fixture is occupying the same 3D location as the floor. If this was what folks were saying was "blocking", I now get that. I was of the impression blocking literally meant something in front of the fixture. In this case, the fixture (light source anyway) was located IN the floor, unable to shine through. My test model only had the same simple GWB ceiling, but no floor system directly above it ... hence no 'swallowed' light fixture!

My workaround was this ... I simply (temporarily) eliminated the floor framing (where the light source was situated) in the floor family, thus creating a "void", and the lights 'rendered' pretty much as expected.

[Anonymous]

Glad you got it working. Indeed, lights being in things is one ofthe most common source of darkness.

You can change the light type to a spotlight to get better results or better yet, use a photometric web. Any light that does not use a photometric web is basically BS, but it will do the trick in most cases despite the photometric innacuracy.

For the future, reveal your light sources in sections to troubleshoot, it will save you a lot of time 

[steve]

Thanks for the tips, very helpful! Is the photometric web, the choice highlighted below?

[Anonymous]

Yes, it wil bring up a new option in your properties for a photometric web.

Then you can point to an ISE file of the light you want to reproduce. For example you can pick a light from Kurt-Versen, find the right photometric web and add it. The rotation angle for IES files is usually -90 degrees (weird, I know).

http://www.kurtversen.com

It's a bit of a complicated pain if your IES came from an LED fixture. For now, jsut avoid LED IES files or else your ligths will come out as reverse rainbow colors.... Good old Revit.

If all this is to complicated, jsut pick the beam on the left of the phometric button. This is more begginer friendly, despite impossible lighting.

[barthbradley]

I have no idea what is being espoused here in my absence, but here are 2 rendering images from the RVT file (Test Lighting.rvt ‏9676 KB) that @steve uploaded to this site yesterday. Nothing whatsoever was done to the Family or the Project. One is a Raytrace (approximately 1 minute), and the other is a Render in Draft mode for Screen resolution.