19 December 2008

Lighting A Bedroom

This tutorial needs you to understand basic use of 3dsmax. If you are unfamiliar with Radiosity, please refer to our previous tutorial Introduction to Radiosity and Simple Light Setup in Radiocity.

Lighting A Bedroom Part 2This time we will try to light a simple bedroom scene using Radiosity. This bedroom has specific characteristics, a large opening on the side. This tutorial will be divided into 2 Part. The first is trying to light a bedroom using indoor lighting. The second covers how to light a bedroom using external light source (sunlight from opening).

1. First, download simple bedroom scene here (3dsmax format, zipped, 68kb). You will notice that all objects in this scene is very simple. Mostly created from box. All objects in this scene also has been textured using standard material available in 3dsmax. When you load this file, 3dsmax may asked you about Unit's file. Choose Adopt the File's Unit Scale. When making this scene, I use 1 unit=1 cm.

If you render this scene, you will get something like image below. Pretty ugly, isn't it? Next, you will render this scene beautiful like a pro within simple steps.When you finished this tutorial, you will be able to render any interior scene like this.


2. First step before you begin. Always turn Ambient light into pure black, before you use Radiosity. If you don't, you will get unoptimized rendering result. Go to Rendering>Environment (or press "8" in keyboard). Under Common Parameters, click on Ambient color box and turn into 100% black.


3. Create a light. Use Free Point Photometric type. Place it in the middle of the scene and a little bit below the ceiling. In Intensity/Color/Distribution rollout change Intensity to "lx at". And use this values, lux=250 at 225 cm. Why I use this values, please refer to our previous tutorial Introduction to Radiosity.


4.Now, turn on Radiosity plugin. From main menu, Rendering>Advanced Lighting>Radiosity. When there's a small popup window opened, just click "Yes". In Radiosity Processing Parameters, use Initial Quality=90, Refine Iterations (All Objects)=5 and Indirect Light Filtering=2. These value should provide enough Radiosity result quality.


5. Press Start button to begin calculate Radiosity solution. When calculation finished, press Render. You will get a darker rendering like image below.


6. Open Radiosity Meshing Parameters rollout. Enable Global Subdivision Settings. Use Maximum Mesh Size between 25-30. Deactivate Shoot Direct Lights option. If you activate it, this option will brighten your scene a little bit. But I prefer counting only indirect light rays.


7. After you changed any Radiosity option or Light properties, you need to re-calculate Radiosity solution. In Radiosity Processing Parameters, click Reset All. Then click Start button again. When finished, all object in viewport looks subdivided.


8. Click Render. You should have something like image below. A slight increase in quality rendering. But still too dark.


9. In Radiosity Processing Parameters rollout, click "Setup" button right next to Logarithmic Exposure Control. Environment window will show up. Increate Brightness to 65. And to remove collor bleed, activate Color Correction. Click on color box, and change its color to bright brownish yellow (R=251, 242, 218).


10. Render Camera viewport. Note: After you change exposure control, you don't need to re-calculate Radiosity again. Exposure control just create an image effect.

To increase rendering quality, select Photometric light. In Modify Panel, activate Shadows and use Area Shadows type. In Radiosity Processing Parameters rollout, click Reset All and Start. Then render again. Image below shows your current rendering.


11. If you like to experiment, you can achieve different style of rendering result. Logarithmic Exposure Control is great, but tends to be monotonous. More dramatic range of color rendering can be achieved using another exposure control. We have another option like Linear Exposure Control and Automatic Exposure Control. The other one, Pseudo Color Exposure Control, most likely never be used in production rendering.

Automatic Exposure Control usually gives more high contrast than Linear Exposure Control. Thus, Linear Exposure gives more softer looks. Now, change Exposure control into Linear Exposure Control. Use Brightness=55-57 and use Color Correction (R=246, G=227, B=185).


12. Press Render again. This image below shows your final render. Next, in Part 2 you will learn to light a bedroom scene using a sunlight coming through windows.


Download Part 1 finished file here (3dsmax, Zipped, 69kb) . (I disable Radiosity solution in this file. To render, you must go to Rendering window (F10), open Advanced Lighting tab and calculate Radiosity solution by clicking Start button. Then, press Render).

This file already has one Photometric light. You will not need this light anymore. Select that light and delete or turn it off.


2. Now, we need to create another light system. We will use Daylight system. Daylight systems use light in a system that follows the geographically correct angle and movement of the sun over the earth at a given location. In Command Panel, click Systems tab. Then, click Daylight button. Click twice in Top viewport to create Daylight system. Don't bother to create exact location of this Daylight System. We can adjust its location later.

Daylight system consist of 2 part, sunlight and skylight. Sunlight is like the "sun" that lit the scene (Direct Light). Skylight on the other hand gives indirect illumination to the scene. Actually, in Daylight system you can choose location, date, time, and compass orientation. This is useful when you want to study shadows in some location. For example, you design a building in San Francisco, you can have exact "sun" movement in San Francisco using Daylight system. For this tutorial, go to Modify tab, and use Manual option in Daylight Parameters. This way, you can simulate daylight without given exact location.


3. Now, move Daylight and its target. Make sure its target is in the middle of the scene and shot from above. For example, I set Daylight system to shot from upper left corner (in Top and Left Viewport).


4. Open Rendering window (F10). Open Advanced Lighting tab. In Radiosity Processing Parameters, click Reset All button. Then, click Start to calculate Radiosity solution. In Interactive Tools, click Setup button. Change exposure control to Logarithmic Exposure Control. When finished, click Render. You will get over-washed scene like image below.


5. Now, open Logarithmic Exposure Control Parameters again. This time, activate Exterior Daylight. Click Render. But this time, the scene looks too dark.


6. To fix dark rendering, adjust Brightness in Logarithmic Exposure Control to 85. Render again.


7. Last step, use Color Correction to remove orange color. But be careful, if you took a lot of orange color, you may get unexpected color, like bluish color in image below. Just use pale orange color to remove a little bit of orange color. Actually, this isn't the desired result I want. Next, I will try using another Exposure Control.


8. Change exposure control to Automatic Expose Control. Set Brightness=62, and use Color Correction to remove orange color (R=239, G=211, B=166). Do a test render again. Your scene is now looks more natural. But, I think the sunlight is too bright and the wall that near window should be more bright than other area.


9. To enhance the rendering, we will use different type of Sunlight and Skylight. Right now, we use Standard sunlight and skylight (not Photometric), that are not optimized using Radiosity. Select Daylight system, and go to Modify tab. In Daylight Parameters rollout change Sunlight=IES Sun, and Skylight=IES Sky. Btw, IES stands for Illuminating Engineering Society. In Sun Parameters rollout reduce Intensity to 2000lx. Then in IES Sky Parameters, set Coverage=Partly Cloudy to make softer illumination.


10. When finished, go to Radiosity Processing Parameters rollout. Click Reset All and Start. Then click Render. This image below show your pro-like rendering image. You have finished this tutorial. In this example image below, I add background image for finishing touch (Rendering>Environment, choose background image file in Environment map).


Download finished file here (3dsmax, Zipped, 80kb). (I disable Radiosity solution in this file. To render, you must go to Rendering window(F10), open Advanced Lighting tab and calculate Radiosity solution by clicking Start button. Then, press Render).

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