Raytrace question

[ARCHIJEF2000]

When a light source is added to an existing lamp, and when this light has identical position and properties. does this impact on the raytracing resources in terms of how long it takes to complete the image.

[icy]

Almost certainly,
But why would you want to do that?

[ARCHIJEF2000]

Because I find it this is the way to increase brightness, it seems to work better than raising the slider. but what do we have: 2 lights, or one light which is twice as bright. and how does the ratrace engine handle this.

[lbuttery]

Well, considering that a Raytrace is just that where EACH ray of light is traced to calculate where it lands and what shadows it creates etc. I would venture to guess that it considers it to be two lights with twice as many rays to be traced.

Lew

[dgavin]

Jeff,

The 2nd light could be set to any type with all the options for strength, tilt, etc. I sometimes will make a fixture to have one spot and one point so that it gives a more realistic look. A pendant with a white glass globe will allow light to emit all around it so a spot light will not look realistic. It is not Pov-Rays job to figure what I want, only to process the information on the lights.

Is that Narcissus you posted?

[WendyWelton]

Jeff,

I'm 99% sure that Chief will trace the rays for each light separately, and it will therefore increase your render time. Computers are dumb robots. There would be nothing to tell it to combine them into a single light source.

[Larry Kumpost]

I would make the original light brighter but if you really want to do it you could set the light so it does not cast shadows. I'm not sure but that might save a little time.

[JeffM]

Conceptually speaking, raytracing time is directly related to the number of lights and reflective/transparent surfaces. Increasing either adds to the workload of the raytracer.

I do not know if the raytracer optimizes the coincident light case or not.

[Dean]

An ambient light (no shadows or attenuation) will not add nearly as much overall ray tracing time as a full shadow light source. Maybe 2 - 5 % is all. Ambient lights are a good way to fill (read as lighten) a scene and eliminate radiosity artifacts when using the low or medium setting without adding too much extra time.

attenuation with a value of 1,0,0 (or higher like 2,0,0) on a 100% light will also ray trace quickly since it does not reach everywhere like sunlight may.

[cgirerd]

And my personal favorite cheating way to save time with raytracing - brighten it up in your paint program with a "lighten shadows" command! That aside, I almost always use some non-shadowing "add lights" placed around the scene for general purpose brightening.

Christina

[MPDesign]

I am curious how long it does take to render in povray?

Michael

[Allen Brown]

Anywhere from 5 minutes to days. It depends on the settings and complexity

[ARCHIJEF2000]

Of course what I should have done in the first place is some experiments. I set up a few tests scenes, and although far from comprehesive, they do show extra lights always add extra time.

[MPDesign]

Jeff,

How long did your machine take to render that scene?

Michael

[ARCHIJEF2000]

Michael , I'm sorry which scene