Light and Water

Announcements, requests and support regarding SkIndigo - the Sketchup / Indigo exporter.
Post Reply
4 posts • Page 1 of 1
rchapman
Posts: 13
Joined: Sun Apr 20, 2008 5:39 pm

Light and Water

Post by rchapman » Tue Apr 22, 2008 5:45 pm

playing around with some water and lighting effects. i got the light from the 3d warehouse and applied some materials via the material editor "presets".

it turned out ok, except a couple of things.
1) how do i make the scene brighter. i gave the lights a "100W" material, is there a way to kind of brighten the scene and make objects reflecting the light more prominent?

2) how do i do a believable water rendering. i drew a shape (with no thickness, does that matter for water?) and used the paint bucket to give it a water material, then used the skindigo water preset on that surface, and it didn't render quite well.

3) in the tutorial with the lights, it said to check the "black" checkbox. can someone explain what this does? also, i found it helpful to also check the "sketchup background color". it looks like checking those boxes work for having the light fixture render the scene, but what exactly do they do to make it work?

thanks all
Attachments
im1208800370.png
im1208800370.png (134.82 KiB) Viewed 3550 times

User avatar
Pibuz
1st Place 100
Posts: 2646
Joined: Tue Dec 11, 2007 7:58 am
Location: Padua, Italy
3D Software: SketchUp

Post by Pibuz » Tue Apr 22, 2008 8:07 pm

Hi Rchapman (you gotta tell us your true name, one day or another.. :D ); i see you're going on experimenting indigo: glad you like it!
I think i have the answer for all of your questions:

1. Your scene looks a bit dark because you probably haven't modeled an enclosed room. With an open space behind the camera, your light won't bounce anywhere, so it can't light up your render. Try putting your light fixture inside a cubic room, go inside the room and render: you'll see the difference! You can try to brighten your scene by choosing a longer exposure time, or increasing the ISO of your virtual camera, but i think you would probably get a "burned" area near the source of light, and around it. However, just try it out to make yourself an idea of what the parameters control. There is a third reason why your scene seems black, but i'll answer you at the point 3.

2. To tell the truth, I haven't understood well how to use the water preset myself. I can surely tell you that a little step towards realism is achieved if you:
a. create a plane (white face upwards, back face downwards)
b. give it a material
c. edit skindigo mat by assigning it a bump map.
You know that if you assign a sketchup color as a material, indigo won't export any UVW mapping of the surface given that specific material, so you'll have some problems finding the correct size of whatsoever texture you want to put on it, either a bump and an exponent map. To avoid this, i suggest you use the same texture you want to put as the skindigo bump map as the diffuse texture for the sketchup water material, so you can adjust it to fit the correct size. Then, double click on water sketchup material, set it to a dielettric preset, set the IOR to 1.33 and choose the right bump map in the bump map slot (don't forget to specify a value, and to keep it low).
You should now have a water looking material.
For all what concerns water preset, let's wait for CoolColJ and Whaat to explain us some more things about its use!! :D :D

3. You know that by default skindigo exports the sun/sky parameters according to sketchup hour of your scene. Another default is the reinhard tonemapping, which has an auto-exposure utility incorporated. Auto-exposure means that the light sources of your render will be somehow balanced to achieve an image not too dark and not too bright (as light sources i mean SUNLIGHT and MESH LIGHTS). This is very useful for very complex scenes, and to get an idea of what the render will look like without losing precious time adjusting the settings of a virtual camera. At the other hand, the image will result a little flat, that is a logic consequence of light power balancing. This tonemapping can instead lead to "errors" when in the scene you have the sun light AND various mesh lights at the same time. In this case, the tonemapping has to balance the exposures of light sources with BIG power difference (sun and lights): the result is that the sun will be ok, but your lights will appear turned off, even if you've correclty set their poer and efficacy. To have them bright using the reinhard tonemapping, you'll have to detach from reality and pump up the mesh lights' power value considerably.
In one of the tutorials, you've learned that skindigo could export also the "sky dome" only: it means that selecting "sketchup background color" in the ENVIRONMENT tab of skindigo (and setting a simple color as the sketchup background color: STYLES -> EDIT -> BACKGROUND SETTINGS) skindigo itself won't export the "physical sky" settings, but only a diffuse-colored dome which will light your scene. So you won't get any sharp shadows, but only a global illumination, as you can see in a very cloudy day. I can't assure you that it will behave properly, because i remember that some time ago this skindigo option had some little problems, and i don't know if it has ever been fixed. I think so, but i'm not sure..
The sketchup background colour can be set to black directly in the ENVIRONMENT settings dialog of skindigo (without the need of setting a black background color in sketchup). In this case, no light apart from MESH LIGHTS will be exported and rendered. In fact, if you set the black background in the skindigo settings tab, and you don't put any other light source in the scene, indigo will report that no light is present in the scene and that it can't be rendered.
In your scene, you've been suggested to put a black background color to have no other light source in the scene excepted your mesh lights. Probably, you haven't changed any tonemapping parameter, so it's still REINHARD, which balances the power of light sources to achieve the correct exposure. But in the scene there is no other light source than your three mesh lights, so their power is conserved.

I think that's all. I hope i've been of some help.

crojack
Posts: 396
Joined: Tue Dec 04, 2007 1:48 pm
Location: Portland, Oregon
Contact:

Post by crojack » Wed Apr 23, 2008 6:29 am

wow, thanks Pibuz, there is a lot of good information in there!

rchapman
Posts: 13
Joined: Sun Apr 20, 2008 5:39 pm

Post by rchapman » Wed Apr 23, 2008 7:42 pm

"c. edit skindigo mat by assigning it a bump map.
You know that if you assign a sketchup color as a material, indigo won't export any UVW mapping of the surface given that specific material, so you'll have some problems finding the correct size of whatsoever texture you want to put on it, either a bump and an exponent map. To avoid this, i suggest you use the same texture you want to put as the skindigo bump map as the diffuse texture for the sketchup water material, so you can adjust it to fit the correct size. Then, double click on water sketchup material, set it to a dielettric preset, set the IOR to 1.33 and choose the right bump map in the bump map slot (don't forget to specify a value, and to keep it low).
You should now have a water looking material. "


can you explain UVW mapping, bump map, exponent map, and how to make something a dielectric preset? im still pretty new, and the tutorial barely touched on them, not in depth enough for me to fully understand. thanks for the other info though, a little over my head, but i'm sure it will prove useful later when i become more experienced.

Post Reply
4 posts • Page 1 of 1

Who is online

Users browsing this forum: No registered users and 24 guests