Exercise 1b: RelightLab

The software that we will be using in this chapter is called RelightLab and is provided by the Visual Computing Lab in Pisa, Italy. It is free!

Installation

You can download the latest version of RelightLab here. Just choose your platform and find the appropriate file. So for example for Windows, you download the file extended with the term "-windows.zip", download it and unzip it somewhere. You don't need to start any installation procedure, just unzip it. To start the software, simply click on relight.exe.

Building the RTI

So first we need to open up some images. Click on the New prject... icon or press CRTL+N. Navigate to your colour-corrected and lens-corrected images and open them. In the list to the left, all the pictures should appear and in the main window the first picture should be visible. Note, that you can click through the list on the left and see the corresponding image in the main window. If you do not want to use any of the pictures in the list, you can click the little x besides it, and it will be ignored.

Adding spheres to the software, so it can start the highlight detection.

The next step is to specify the position of the sphere(s). Yes, that's right, with this software, you can finally use multiple spheres! Click first ob the little sphere on top of your file list and below the Sphere list. You can now specify three points in the image to form a circle. The points should be positioned at the edge of the sphere. Try to click on three separate points, until you see the whole circle around it. If you are not happy, you can still manipulate the circle or delete your sphere in the Sphere list by clicking on the trash can. You can also add more sphere and simply repeat the process.

Highlight detection done.. Check if everything is in order.

You can now start the highlight detection. Simply go into the menu and hit Edit/Find highlights. It takes a moment, but is much faster than before. When it is done detecting, give your file list a quick look. Select a couple of images and look if the green crosses are at the highlight position of the sphere. If not, you can manually adapt them by using your mouse. Sometimes the highlight detection doesn't find any highlights on a sphere. You can either redo the process and make the yellow circles around the spheres bigger, manually adapt the highlight to the correct position or simply remove that one image from your file list, as described above.

Cropping and selecting the export option.

We now finally only need to export the RTI image. So RelightLab has several options, but I will discuss only two here: RTI image export and Openlime Export. Both exports can be done in one step. so first click in the menu on Export/Export RTI.... A new window appears with many option. Don't worry so much about them. First select RTI in the Format list and also check the Add Openlime viewer option. If you want, you can also crop the image now, as we don't need to see all of it as a result. When you click the Crop button, you see a little window on top of your image. Resize that to the portion you want to keep. Finally, click on Build and select a folder where to save to. When RelightLab is done, you can either save the progress or simply close the software.