Digital Art Zone

Here is a picture where I replaced the UALP around the camera with a spot light that is at the same location and pointed in the same direction as the camera (something you cannot do with physical lights and cameras). I used the same slightly pink color and 50% intensity. There is no UE2 ambient light in here, so it should be compared with the image above before I added UE2 ambient.

The main difference I see is the spot light has blown out the walls, especially behind V5’s head. The spot light has no falloff ends feature, so you cannot limit the illumination of the walls behind. The extra control of the UALP however comes at a price. The render time on this image with the spot light was only 1m 33s compared to 5m 50s with the UALP. (Note I may have cranked the samples up higher than needed on the UALP. I had it at 64.)

Objects like walls etc, can be set to not cast shadows which allows the light to pass through them.

Gedd - 03 December 2012 08:35 AM

Objects like walls etc, can be set to not cast shadows which allows the light to pass through them.

I haven’t tried lighting, but the question begs- “How?”  Is it something easy to find and do?

As long as they are separate objects the casting of shadows is a setting in the Parameters pane - if they are part of a single item then it takes a special shader to be able to turn shadow-casting off.

Thanks, I hadn’t run into this and would have been scratching my head probably when I did.

I’m guessing here, depending on the surface one wants to pass light through, one could use the surface selector, make that surface invisible and replace it (with a primitive plane for instance) that could then be set to not cast shadows. This would only work where one could feasibly replicate the area to pass light through ofc.

On a separate note, I just had a thought. There has been an ongoing debate for (forever) on what to do when a ‘feature’ doesn’t apply in a given situation. Does the developer just remove that from the menu or, grey it out. Neither one addresses the problem of someone trying to understand ‘why’ a feature isn’t available and this has been at the crux of the problem. What just occurred to me was, a developer could have the option grey out (when possible, sometimes this isn’t an option) and have it so if someone clicks on the greyed out link, instead of getting nothing, it popped up a best available info box on why the feature wasn’t available. Then, to allow advanced users to streamline their interface, have a feature in the preferences that allowed the greyed out menu items to just not show at all.

I just wanted to jot that last item down as it has been a bugaboo forever and I haven’t heard a solution to it, so wanted to put it down before I forgot it. (I’m big into usability.)

Gedd - 03 December 2012 08:35 AM

Objects like walls etc, can be set to not cast shadows which allows the light to pass through them.

I’m confused as to why I would want light to pass through my walls.

Is this so the outside light gets into my indoor scene?

Will the light really pass through the wall even though the opacity is set to 100%?

Does this apply to ray traced lights, like distant lights that are set to cast ray traced shadows?

Does this mean both the light and the object have to be set to cast shadows?

It is common to set a ground plane to not cast shadows, then put a ‘bounce’ light under the ground pointed up to illuminate from below similar to a box light in a studio. Unlike a studio one has much more flexibility in where the light is put, so a single light can evenly light an area that a single box light couldn’t in real life. If the outside surfaces that don’t need to cast shadows are set to not cast shadows, then one can use global illumination type techniques to more easily set a base ambient level and then use other lighting to sculpt the lighting to the scene. Basically, ambient light is not correctly accounted for in 3DLight. I’m not blaming the render engine but it’s the case. We have to create our light environment, and it doesn’t exactly mimic nature so we have to learn the engine and work with it. This actually has an advantage in that once we do learn how to work with the engine, we have much more creative freedom then if it did mimic nature and didn’t allow us to manipulate the light envelope to the extent we can in engines like 3DLight.

Another issue is, any surface that we don’t need to cast shadows, if we turn cast shadows off for that object/surface it is supposed to speed up render calculations as the engine doesn’t have to take that into account for that surface/object.