PanoRendo is an HTML/JS application which can be accessed by the WEB browser of any device to simulate the sky brightness and colors, including daylight & twilight. Parameters such as Sun position, observer altitude, type and amount of haze can be freely modified (JavaScript must be enabled). PanoRendo has three different tone-mapping options with adjustable brightness. The view screen can be chosen as panoramic to cover all of the sky, or zoomed to explore the horizon in detail for the twilight. Besides the rectangular views, it incorporates a fish-eye mode as well. PanoRendo uses a fast single-pass rendering algorithm. Detailed explanation about the employed sky model can be found in the relevant paper. A spreadsheet in MS Excel format is also available.


Sun Elevation and Sun Azimuth angles can be altered between -20° ~ +90° and -180° ~ +180°, respectively. The elevation above sea level can be entered into the Altitude box. The Haze field changes the turbidity of the air. The minimum value of 1 implies a "clean & dry atmosphere" (pure Rayleigh scattering). Any value greater than one sets the amount of aerosol (Mie scattering). The absorption characteristics of the aerosol can be controlled by the slider bar Absorption. The left-most position is suitable for fog/maritime, whereas the right-most position implies urban pollution/smoke. For rural atmosphere, the default middle position is recommended. The brightness can be boosted by increasing the value in the Luma field as to analyze e.g. a twilight condition in depth. The sample picture above is a panoramic snapshot for a sunset, where the Venus Belt can be discriminated. The below one is a zoomed view for a hazy sunrise.


The tone-mapping curve is selected on the drop-down menu Gamma. "Low" outputs linear RGB with gamma=1, "High" option compresses the scene with a gamma value of 2. The option "Hue" applies the gamma compression only to the luminance as to maintain the chromacity. From the drop-down menu View, the projection type can be picked. "Panoramic" implements the equi-rectangular projection with a full Field-of-View (360° x 90°), while the "Zoomed" option decreases the FoV by a factor of 3 (120° x 30°). The "Fish-eye" selection enforces the polar orthographic projection, with the zenith at center and the horizon on circumference, as shown below.



Click to go to the PanoRendo application