[Jonathan B]

Hi,

I want to clarify an issue with emitters...I have created a single group for an emitter which is made up of an open cone shaped light fixture with a mirrored inner skin (which a fellow Maxwell user recommended i do) and a small polygon emitter inside which has approx 14 faces. I have applied a material to the emitter with a wattage of 100 and efficacy of 50. I have then copied the light into a number of positions to use it as light for pendants and giving general light around a room.

Will each light have a wattage of 100 or will it share the wattage between all the lights if it is use the same emitter made from one material in sketchup? I can never remember when it shares wattage power and when it doesn't!



When i am just using the emitters to light a scene I find that there seems to be more noise than when using just the sun or both emitters and sun. Is there any reason for this? perhaps i have set the emitter up wrong? These are quick renders on drft engine up to around 8 SL but they give the idea.... the EV is 10 in both



compared to this with the sun



Thanks,

jonathan

[JDHill]

Each object using the material will emit the value specified in the material, so it comes down to how you group things: given a 100W emitter material applied to a group directly containing 10 disjoint faces of equal size, each face will be seen to emit 10W (if not disjoint, the faces basically make up a single object, which will output 100W). Were each face made its own group, though, then each would be an individual object, and would output the full 100W. This has purely to do with the construction of the meshes used by the engine, so it applies only at the level of the face container, whether that is a group or component, and not further up, say when several groups are further grouped or put into a component.

Regarding noise, the keys here are to minimize the number of emitting triangles, which you are already doing with decently low-poly emitter geometry, and to use the Production engine, which is much quicker at resolving more complex lighting scenarios (it is generally going to be slower to respond, though, and will render darker at the lower SLs, which are reasons why the Draft engine is more appropriate for use when working on the scene, as opposed to rendering to produce a final image).

[Jonathan B]

Ok great so each of my emitters will be emitting 100 Watts at 50 Efficacy.

Would you recommend using an IES file in this situation, and does it have any benefit over the emitter light that i simply created?

I'm assuming that the benefit of the IES is that it gives you the light effect that it shows in the preview of the plugin?

Thanks

[JDHill]

The main point of IES files is to reproduce light in a given pattern, which was likely measured by the manufacturer. Probably, I'd just suggest that you give them a try and see how they work in this particular scene.

[Jonathan B]

Hi,

I left two production renders on over night on SL 18 on two separate machines (one desktop, one laptop), and I have just come down to notice that both have disappeared and sketchup shut down but my other windows (mail and chrome) are still up. Any idea why this might have happened? Can I see in task manager any programme failures etc?

Thanks

[JDHill]

I couldn't say -- that's definitely not something expected. It might be that you could learn something about it by going to Control Panel > Administrative Tools > Event Viewer, and looking through some of the application logs, but I don't expect they will tell you much. If something like this happens, one thing to do would be to have a look at Documents\Maxwell\SketchUp\temp\temp.jpg -- that is the temporary image written at each sampling level, in order that the rendering might be shown in the Maxwell Fire window (it has to be put somewhere on disk, since the window is really a web browser).

[Jonathan B]

Thanks for getting back in touch so quickly, indeed as you mentioned the event viewer has information on it but it's all a bit too techy for me to understand what it's saying! It mentions errors and warnings during the stages of the night but nothing i can understand. It's very strange, especially that it happened to both machines!

The temp file was at a fairly early stage by the looks of it (on the laptop - i'll have to check my desktop tonight when i get back to see the stage of that one), but that is good to know it does save a backup file for future reference.

So bit of a mystery, hope that doesn't happen again!

JB

[crcgrp]

So, just to clarify about emitters. If you want 5 emitters at 100w each, then you need 5 single planes, each it's own group. If you put 5 single planes grouped together, even if they aren't touching, they would equal 20w each? And can these 5 single planes be individual components and it all works the same, or does it have to be groups?

[JDHill]

If you put 5 single planes grouped together, even if they aren't touching, they would equal 20w each?

Correct (provided all 5 faces are of equal area), because all faces contained directly in a group become part of a single mesh. And a mesh need not be composed of contiguous faces, since it is really just a list of triangles in space.

And can these 5 single planes be individual components and it all works the same, or does it have to be groups?

Internally, in SketchUp, groups and components are basically the same thing, except that there can only ever be one instance of a group, meaning that the above applies equally to faces contained directly in groups, or directly in components. So if what you mean here is that you have 5 components, each containing a single face, you would have 5 meshes, each emitting the full 100W.

[crcgrp]

If you put 5 single planes grouped together, even if they aren't touching, they would equal 20w each?

Correct (provided all 5 faces are of equal area), because all faces contained directly in a group become part of a single mesh. And a mesh need not be composed of contiguous faces, since it is really just a list of triangles in space.

And can these 5 single planes be individual components and it all works the same, or does it have to be groups?

Internally, in SketchUp, groups and components are basically the same thing, except that there can only ever be one instance of a group, meaning that the above applies equally to faces contained directly in groups, or directly in components. So if what you mean here is that you have 5 components, each containing a single face, you would have 5 meshes, each emitting the full 100W.

That's what I meant. The reason I was wondering about the component/group is that it is easier with multiple emitters to change them if they are components. This clarifies a lot. Thanks!