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Light

Almarea Lumiere
Registered User
Join date: 6 May 2004
Posts: 258
06-06-2004 22:41
I'd love to have our cottage to look nice and cozy at night, when we're inside. I've been playing with light, trying to get it to look natural.

Goodness! This isn't the kind of light my mother taught me about!

One thing that's worked great is putting light sources in the attic, above the ceiling. The ceiling doesn't block the light at all, but it hides the real light sources. Putting several sources of different sizes creates great pools of light scattered around the room. Later, we will be able to add faux track-lights which will seem to provide the illumination.

This doesn't light the bottom of the ceiling (it's facing away from these sources so you wouldn't expect it to, never mind that anything other than the other side which is on the other side is lit just fine), so there needs to be a light source in the floor to throw a little light on the ceiling. Here's a picture of the ceiling, lit by a plate from beneath.

Look! Three different light intensities! It appears that, in addition to intensity falling off with distance it is also depends on the size of the object (larger is dimmer, and ten meters -- on the left -- is very dark) and (in _addition_ to the inverse square business) it gets additionally dimmer the farther the center of the object is from the light source.

Help! Is there any way I can keep the ceiling lit uniformly? It is more than ten by ten, so it needs to be in more than one piece.

So. Do we all like how this works? Far be it from me to call something a bug after only having been here a month!

I can understand prims not casting shadows, but this business with intensity doesn't make any sense (I've seen something similar even by daylight).

I don't suppose it's just my pesky Radeon chip?

--Almarea
Salazar Jack
Nova Albion native
Join date: 12 Feb 2004
Posts: 1,105
06-07-2004 14:41
I don't know if this will help at all but you can make lights 100% transparent and make them phantom so you won't see the light source and you can pass right through it. Then you can place it anywhere you want. It still puts out the same amount of light (depending on how large the object set to Light is).

To set the light-emitting prim to 100% transparent you have to upload a completely transparent Targa image (.tga) or acquire one from another resident.

Hope that sheds some... light... on the matter.

Salazar

p.s. If I'm just being a dim bulb and this is basic info that everyone already knows, feel free to roll your eyes and wait for someone with more wattage. - S.J. (Can I also just say that I chuckled when someone with your last name had a question about light.)
Almarea Lumiere
Registered User
Join date: 6 May 2004
Posts: 258
06-08-2004 19:19
Thanks, Salazar, invisible lights are definitely going to be part of the finished product!

More nights rezzing by moonlight, more insights into the nature of light in our peculiar universe. It seems as if prims can only be lit from the corners. I took photos of some of the experiments (see attachment). In the first one the light source is right at the corner and it sure does light up the prim. But just moving it a teensy bit away and it might as well not be there at all.

Now move the box just enough to see the corner again. With this photo in PaintShop, it's possible to see the exact color at each point, and (lo and behold) the surface is brightest at exactly the corner, not at the point closest to the light source.

The graph at the end shows luminosity based on distance from the corner. At exactly halfway (as it seems in the photo) the light just stops. And see how the drop-off is linear and not inverse-square at all. Hue was constant (at 20), but saturation had a bit of an odd curve, as you can see.

Lighting two corners creates a gradient from one side to the other, four creates uniform lighting on the surface.

Getting the ceiling to look good is going to be a challenge. Putting a light at each corner of the plate will work, but it will light up all kinds of other things as well, sometimes inappropriately. Pools of light (the kind you see on the ground outside) seem right out. :(

Although I was probably named after a talking candle, I'd prefer to think that I'm following in the footsteps of Auguste and Louis (also appropriately named), pioneers in motion picture technology, one of the big steps forward in the creation of virtual worlds!

--Almarea
Almarea Lumiere
Registered User
Join date: 6 May 2004
Posts: 258
06-10-2004 20:44
Sunlight casts shadows.

Primlight does not (nor moonlight it seems), though it lights the near surface of nearby objects (and whatever is on the other side of them as well).

Trees are sensitive to the sun and moon, and in some ways to prims, but they don't take color like the ground and other prims.

Particle light does not even light anything up.

Light and shadow only affect the vertices of prims. The intensity at the vertex is shaded into the adjacent faces. This means that a large floor-board in sunlight can be significantly dimmer than the one next to it if it is even a bit lower, and the corners are in the shadow of the one next to it. This is a constant source of frustration, since it is necessary to create large floors from many prims, and it would be nice if they looked seamless.

The ground, on the other hand, seems to take shadow point-by-point, so that you see a dim outline of what the shadow of a prim ought to be. But cutting or hollowing the prim doesn't affect the shadow it casts (which can possibly be used to good effect).

The shadow is a bit smaller than the prim, so a prim needs to be a certain minimum size before it casts a shadow at all.

It seems that, if the inside of our house is going to look good at night, we will need to have a lighting plan which takes account of all of the prims, before we even start building.

I really want primlight shadows. :( The cottage is not going to look really cozy till light is streaming out of the windows onto the porch at night!

--Almarea