This tutorial takes you through some important aspects of modelling a more complex space.  The Lightscape model is called "tut3.lp"   - the  data files for the tutorials may be obtained from the computer "ariel" on the EVDS network.  You will probably have to use the Windows search utility to locate this computer.  The files are in the directory "617 tutorial files" which, in turn, is in folder "jlcourses"

Copy files "tut3.atr" and "woodfloor.jpg." to your working directory, as well as the six "picture" jpg files as they will also be required.

Radiosity and ray tracing are two important terms in rendering of computer models. Radiosity is a technique for computing the exchange of radiant energy (light is visible radiant energy) by breaking surfaces into small patches (elements) and iteratively calculating the exchanges of energy among all patches. Once analyzed by radiosity, an interior can be viewed from any angle without re-computing the energy exchanges. However, it does not handle specular reflection of light. Raytracing is based on tracking selected rays of light from the "eye" (viewing position) to the surfaces (following the reflections that occur along the way), which is backward ray tracing, or from the surfaces to the eye, which is forward ray tracing. Specular reflections are handled. It is more computationally intense than radiosity and is dependent on the eye position. Lightscape can use a combination of the two.

Part I - Creating a Material by using an Existing Texture Data File 

1. Launch Lightscape and open "tut3" in your working directory.
2. Click the right mouse button anywhere in the Materials Palette to open the related menu.
3. Select "Create" from the context menu. A new material, called "iteml7" is added to the table and highlighted in blue. You can now enter the desired name for the material.
4. Change the material name to "FLOOR_WOOD1"	If "Item17" is highlighted, type over it; if it is not highlighted, right-click on it and select "Rename" from the context menu
5. Using the left mouse button, double-click on FLOOR_WOOD1 Select "Wood Varnished" from the Templates pull-down menu.	A "Material Properties" dialog box appears. After you make your selection, the various parameter sliders are marked with red and green lines. The green portions of these lines represent the valid range of values that you should use when defining the desired material. Notice that the "Hue" (H) and "Saturation" (S) sliders of the reflective color have no lines. This means that you can use any values. "Value" (V) is used to represent the amount of visible radiant energy (light) that is reflected from a surface (reflectance). A material with a "Value" of 0.2 will reflect 20 percent of the energy and absorb 80 percent of the energy that it receives. Assigning a reasonable Value for a material is particularly important in obtaining a valid lighting simulation. Many materials contain patterns or textures. A wood floor is a good example of such a material. To define these materials you can use image bit maps (called texture maps) to modify the color of a material across a surface.
6. Click on the Texture tab. Click "Browse" Double click on "woodfloor.jpeg" in the "File Name" list. Set the Brightness slider scale to about 0.25 so that the average reflectance of the texture is  about 0.209 and the Maximum reflectance (Max.) is about 0.246	A preview of the image of the wood floor is shown on the texture page. When using these textures, make sure that the average Value of the texture is also within a valid range for the type of material it represents. This range is indicated in the Value slider that can be used to scale the Value of the texture map being used. Texture maps such as these are readily available from a number of suppliers. Some samples are provided with the Lightscape system.

Part II - Saving a Material Definition to a Material Library

Now that you have defined FLOOR_WOOD1, you may want to save it to a Material Library so that you can easily access it later for use in another project.

1. Select FLOOR_WOOD1 in the Materials Table.
2. Using the right mouse button, click anywhere in the "Materials Palette" to open the context menu.
3. Select "Save" from the context menu.
4. Type "floors.atr" for "File Name," select the appropriate directory, and click "Save"	The library is now available.

Part III - Loading a Material Definition to a Material Library
Material definitions stored in a library may be loaded into a preparation file. If the name of the material being loaded already exists in the "Materials Palette", the old definition will be overridden by the new definition. This is a convenient way of setting up alternative sets of finishes for a project.

Material definitions for this project will be loaded in this way. Copy file "tut3.atr" from the computer "ariel" on the EVDS network.  You will probably have to use the Windows search utility to locate this computer.  The files are in the directory "617 tutorial files" which, in turn, is in folder "jlcourses"

1. Using the right mouse button, click anywhere in the "Materials Palette" to open the context menu.
2. Select "Load" from the context menu.
3. Select "tut3.atr" from the appropriate directory and click "Open" Click "Select All" to select all materials. Click "Yes"	An "Available Materials" dialogue box appears. A Lightscape caution appears "One or more of the materials already exists in the current database. Overwrite all? "

Part IV - Displaying Textures

The model will now be processed to display textures. Save it under a new name, so that you can revert to the preparation file if desired. Copy the files "Picture 1" through "Picture 6"  from system drive Courses on Hal in folder Jim_Love_Courses/617 to your working directory (the one in which you have the preparation file for this exercise).

1. Select "Display-Solid"
2. Select "Display-Textures"	The painting images will appear in the frames.

Part V - Processing the Model

1. Orient at least one of the perimeter spot lights so that it is aimed at the center of a picture (if you forget the steps, see part II of Tutorial 2).	The preparation file should be modified to illustrate a few features.
2. Save the preparation file and save to a new name for solution (coming up).	The state of the model prior to any radiant exchanges is called the "zero energy state" (0 iterations)
3. Invoke "Process-Initiate" Click "yes" to save your file.	A "Lightscape" caution dialogue box will appear.
4. Invoke "Process-Parameters..." Leave settings at defaults, except the following parameters in the "Process" area of the dialogue box.	A "Process Parameters" dialogue box will appear.
5. Click on Wizard. Set "Quality" at 3.
6. Click "Next" Select "no" for "Do you want to consider daylighting in your solution?"	A "Daylight" dialogue box appears. This will highlight the effects of the electric sources.
7. Click "Finish" and "OK," exiting the "Wizard" dialogue box.	Before running a simulation, you may request a preview. The "Ambient light " option under "Display" distributes all the undistributed light evenly to all surfaces. If the model appears overly dark or light when "Ambient" is turned on before processing, this indicates that either the luminaires are incorrectly defined or that the model has been set up incorrectly.
8. Invoke "Display-Ambient" De-select "Display-Ambient"	Observe that the overall brightness of the model  is acceptable.
9. Invoke "Process-Go"	The simulation will begin. The iteration number (the number of the light transfer being considered) will be shown in the lower dialogue bar of the viewport, along with the percent of the light energy distributed. It will take about 10 seconds to go through 30 iterations and distribute about 75 percent of the light energy. At around this point, invoke "Process-Stop." In progressive refinement radiosity, the program runs through the sources (emitters and reflectors) based on intensity  and computes the contribution to all surfaces in the scene. The light sources will be handled first, then interreflections among surfaces will be calculated. Note the color bleeding effects as the system distributes the energy to the floor. Note the way the brightness of the surfaces evens out as the energy is distributed among the surfaces. The central ceiling is last to be illuminated, because it receives only reflected light. The message "Preparing to stop processing" appears in the status bar (just below the viewport); when processing has stopped (the most recent iteration is completed), the message "Processing stopped" appears.
10. 9. Invoke "Process-Stop"
11. You may use "Orbit" to move the model around for inspection purposes.
12. Invoke "Display-Original" and "Display-Outlined" - this view will show the form of the patches or surface elements used in computing the radiant exchanges.	Lightscape uses "adaptive subdivision," a technique in which the size of the elements is increased where more accuracy is required.
13. Choose "Edit -Selection" or click the "Select" button on the toolbar. Be sure that selection is set to surfaces Select (left-click) a point anywhere on the floor.	An important feature of Lightscape is the ability to make changes to the surface materials even after starting a radiosity solution. This allows you to rapidly test various design alternatives and make adjustments to the materials and lighting to set the precise look you want. This will be demonstrated by changing the carpeted floor to a wood floor. Note that the floor is now selected.
14. Using the right mouse button, click anywhere in the viewport to open the context menu. Choose "Assign Material" from the context menu. Select FLOOR_WOOD1 from the list. Click OK.	The "Assign Material" dialog box displays. You have now set the material assigned to the floor surface to be a wood floor. To see the texture map on the surface, choose "Display -Texture" or click the "Texture" button on the toolbar. Notice that the color of the floor changes as soon as you redefine the material, but the color of the interreflection from the floor to the ceiling and walls does not change. To update the interreflections, you must run the radiosity processing further. Continue processing a few more iterations (Process-Go).
15. After a few iterations, invoke "Process-Stop" or click the Stop button on the toolbar to interrupt the processing.	Observe the change in coloration in the room. After only a few iterations, you can observe the effects of this material change on adjacent surfaces. The color of the walls and ceiling has changed significantly. This demonstrates an important effect that various materials and lights can have on the overall aesthetics of a room, known as color bleeding. The ability of Lightscape to simulate this effect is one of the key advantages that the software offers over conventional rendering technologies. Another advantage is the fact that, because luminaires can be specified using real-world photometric values (including specifications from manufacturers), you can perform a meaningful lighting analysis of your solution.

You will now perform a lighting analysis.

1. Invoke "File-Properties" Select the "Units" tab. Set "Lighting" to "International" and click "OK"	A "Document Properties" dialogue box appears. This ensures that results are given in SI units.
2. Invoke "Light-Analysis".	A "Lighting Analysis" dialogue box appears.
3. Click on the "Statistics" tab.	You can now use the mouse to call up illumination quantities.
4. Click in the middle of one of the pictures.	The statistics for this surface appear in the "Lighting Analysis" dialogue box. Note that as you click at different points in the picture surface, the "Point" value changes.
5. Click on the display tab. Change the "Display" pull-down menu from "Normal" to "Color" Enter "75" in the "Max" field. Click "Apply"	The viewport image changes to a "false color" display that maps the illuminances (the scale appears at the bottom of the viewport).
6. Repeat steps 4 and 5 with "Max" set to "150" - look for the "hot spots" and note the changes in areas highlighted (i.e., those receiving light directly from sources).
7. Change "Quantity" (in the "Lighting Analysis" dialogue box) to "Luminance" and "Max" to 50 cd/m2. Click "Apply"	The image is similar to the pattern of luminances that can be obtained with a video photometer (a standard luminance meter provides the luminance of only one spot, whereas the pattern of luminances in the entire visual field is usually of much greater value).
8. Change the "Display" setting back to "Normal"

Part VI - Creating and Saving a Radiosity Image

1. Invoke "View-Original"	If necessary, turn on textures ("Display-Textures")
2. Invoke "File-Render"	A "Rendering" dialogue box appears.
3. In the "Output File" area, select "Targa (TGA)" from the "Format" pull-down menu.	TGA is a common bit map image format for windows.
4. In the "Name" field, give the file to be created a name such as "rad1.tga" Click OK.	Lightscape takes a snapshot of the current view and saves the image to disk.

Note: You can further improve the quality of any image you create with Lightscape by using antialiasing to remove jagged edges.  You should use this feature for the images submitted for your assignment.  The higher the level of antialiasing specified, the longer it takes to create the image.


Part VII - Creating and Saving a Ray Traced Image

If you are interested in the highest quality image, then you can use the ray tracer to add specular reflections and enhanced lighting effects. Typically, the ray tracing process used in Lightscape proceeds much faster than traditional ray tracing because the ray tracer does not have to calculate the direct lighting; this is already calculated with the radiosity process. For some light sources (such as sharp spotlights and sunlight), you may want to ray trace the direct light to obtain a better quality shadow.

1. Invoke "Edit-Select-Luminaire" or click the "Luminaire" button on the toolbar.	First, set a luminaire to be ray traced.
2. Select one of the perimeter spotlights that you oriented toward a picture.	The selected luminaire will be highlighted.
3. Right-click in the viewport to open the context menu for the selected luminaire. Select "Luminaire Processing" from the menu that appears. Click the "Ray Trace Direct Illumination" check box. Click OK.	A "Luminaire Processing" dialog box appears. Now, create an image using ray tracing.
4. Choose "File-Render" In the "Ray Tracing" area, click in the "Ray Tracing" check box to turn on ray tracing. In the "Ray Tracing" area, click the "Ray Trace Direct Illumination" check box.	A "Rendering" dialog box appears. This indicates that you want to ray trace any luminaires that have been set for ray tracing.
5. In the "Output File" area, type a name such as "ray1.tga" in the "Name" input field. Select "Targa (TGA)" from the "Format" pull-down menu. Click OK.	If you leave the Name input field blank, the system renders the image and displays it to the screen but does not save it to disk. Lightscape will do an iteration for each light source set for ray tracing. When that is done, the ray tracing begins.

Part VIII- Viewing Images with Lvu

Lvu is a utility for viewing images created with Lightscape.

1. Invoke "Lvu" (from the Lightscape "Startup" area.
2. Invoke "File-Open"
3. Open one of the "*.tga" images created in Parts VII or VIII Double-click on the icon that you wish to see full size.	Thumbnail images will appear.

You have now completed Lighscape Tutorial 3!