LIGHTING DESIGN - Exporting to Radiance

Interfacing with Radiance

In this tutorial you will learn how to export a file to the RADIANCE Synthetic Imaging software and generate realistic lighting levels. RADIANCE is not installed with ECOTECT, however it is a freely available public-domain application from Lawrence Berkeley Laboratories. You will need to have either downloaded and installed the free Desktop Radiance software from the Lawrence Berkeley site or purchased the ADELINE package to complete this tutorial.

1. Open  Classroom.eco  from the Tutorial Files directory located in your main ECOTECT Install directory.
   
   There only two zones in this model, one called Classroom and the default Outside zone.
   
   

Creating a Camera View

1. We first want to set up a camera in order to view the interior of the room.
   
   To create a camera, click the Camera button    in the left-hand side toolbar. To position the base point of the camera, use the Control key to move the cursor up and down in the Z axis and then drag it into position. Be careful not to position it exactly on or in any of the wall, floor or ceiling planes or you will end up looking directly at a flat featureless surface. Once you position the first node, ECOTECT will prompt for a second. Simply drag the 'look at' node to the other end of the enclosure as shown.
   
   
   
   It does not matter if the second node sits on a plane or is coincident with any particular point as it serves only to provide a view direction.
   
   If you need to reposition the camera after placing the second node, simply double-click on the camera object and select either node to move it. The view direction is always indicated by the 'pointy' end (the one with the arrow).
   
   Before moving on and calculating light levels, it is important to make sure that the analysis grid is set appropriately. If the grid is altered in any way after calculations have been performed, the calculated values will be lost. See the Lighting Introduction tutorial if you need more information.

Setting Camera Properties

1. To set the properties of the camera, make sure it is selected and click the Material Assignments Tab icon to display its assigned material.
   
   The Materials Tab is located on the right hand side of the main ECOTECT application window. There is only one CAMERA material in this model so it is automatically assigned.
   
   
2. The next step is to modify the field of view of the camera. To do this simply double-click on the 'External_Camera' entry in the materials list.
   
   You should now see a dialog box like the one below - change the horizontal and vertical angles to 90 and 60 degrees respectively as shown below and click the OK button.
   
   
   
   The camera's pyramid shape should update, as shown below.
   
   

Exporting to RADIANCE

Once you have created a camera, you are ready to export to Radiance.

1. To generate a Radiance image, select the Export... item in the File menu and change the file type to Radiance Scene File.
   
   Basically Radiance doesn't seem to handle long file names at all well. Some of its components do, but things such as PFILT and PCOMB don't. Always save your Radiance scene files in a very simple directory structure (such as C:\temp\rad\run1 or something). Never use spaces in the names or names greater than 8 characters long. Sometimes they'll work, most of the time not.
   
   Once you select a file name the following dialog box will be displayed:
   
   
2. Ensure you change all the settings to match those shown above and then click the OK button.
   
   You should now see a DOS Command Prompt appear and a whole range of command line data display. Radiance should automatically run, which may take a while. However, it should periodically display its calculation status as it goes.
   
   
   
   If you do not see DOS prompt it is likely that you did not select the Save+Final Render option at the bottom of the dialog. If you instead see a dialog box asking you to locate the Radiance Application RAD.EXE, then this is simply the first time it has been run on your machine and ECOTECT has been unable to find the Radiance directory in all the usual places. Simply navigate to where you installed Radiance, enter the bin directory and choose the RAD.EXE file. You should then see the DOS Prompt.
   
   If your DOS Prompt appears and then disappears almost immediately then you are in trouble. We;ve tested and re-tested the Classroom.eco file with Radiance, so you can be pretty certain its an installation issue. You could try selecting the Save + Invoke RadTool option, then set the Pause on Completion option in the Settings dialog box to try to deduce when the problem might be, however you will probably find the information you need in the Square One forum as we get quite a few enquiries about setting up Radiance.
   
   You can get quite comprehensive help on all the settings in this dialog by clicking the Help... button.
   Radiance is an excellent tool for highly accurate and quick lighting analysis, however it can be a little temperamental and takes a bit of getting used to. Whilst you can use ECOTECT to bypass much of the data entry and command line issues with Radiance, however you should have a good read of the documentation that comes with it if you wish to use it for more than simple visualisation.
3. Once the calculation is complete you should see an image very similar to the following pop up in WinImage.
   
   As selected in the dialog box, this is an illuminance image, not a luminance image. This means that it differs from a photographic image by showing the amount of light falling on each surface as opposed to the amount of light reflected off.
   
   

Generating Contour/False-colour Images

The real benefit of this is that you can generate false-colour and contoured illumination maps directly from this image. To do this, simply select False-colour... or Iso Contour... from the Analysis menu in WinImage.

This will display the following dialog:

Ensure you select Illuminance in the Quantity group and enter a Maximum Value of 4000 Lux to set the scale. Selecting OK will display the following image if you selected False-colour.

You can save this image as a Bitmap for inclusion in reports by simply selecting Save As...from the File menu and setting the file type to Windows Bitmap.