Quoted from: https://www.urbanclimate.net/skyhelios/description.htm
Introduction
Graphic processors can be integrated in computation models, e.g. in three-dimensional flow visualization or radiation estimation. Going a step further it is even possible to use modern graphics hardware as general-purpose vector computers. These ideas and approaches use a cheap mass technology to solve specific problems. This technology can be applied for modelling climate conditions or climate relevant parameters on the urban scale or micro scale. To prove this, we have chosen to implement the calculation of continuous sky view factor (SVF) for each point in a complex area, given by a digital elevation model (DEM), urban obstacles (OBS) or other digital files in order to quantify relevant climatic conditions in urban and complex areas. The following benefits are provided from the new model: (a) short computing time (b) short development time and (c) low costs though the use of open source frameworks.
Usage
Importing spatial data
Files of the following types are supported:
Raster files
|
|
Vector files
|
• GDAL formats, e.g. GeoTiff (*.tif) |
|
• CityGML (*.gml, *.xml) |
• tab delimited text files (*.tab) |
|
• RayMan Obstacle Files (*.obs) |
• csv files (*.csv) |
|
• OGR formats, e.g. ShapeFiles (*.shp) |
• text files (*.txt) |
|
• Collada meshes (*.dae) |
• ASCIIgrid (*.asc) |
|
|
• portable network graphics (*.png) |
|
|
Vector files
Vector files can be imported by clicking on the "Vector" button in the upper left corner.
After selecting the file and the hight band, the data can be displayed by clicking on the "Show" button as explained in the "Raster" section.
Using several Raster and / or Vector files together will be easy as long as the correct geographic projection is known and set. For unprojected files you may have to move the middle point of the files to make them match.
Raster files
Raster files can be imported by clicking on the "Raster" button in the upper left corner.
After selecting the desired file, you may have to change some of the settings like hight band, cell size, or the colors.
The "Show" button below the settings will display your data.
Calculate Sunpath and SVF
For calculating the sunpath or the sky view factor (SVF), you at first have to enable the "production mode" by clicking the checkbox below the fisheye image on the right.
Now you are able to click somwhere on the map and the SVF will be displayed left below the "prduction mode" checkbox. For having displayed the sunpath, you aditionally have to check the "Enable Location" checkbox.
Both will be calculated for every point you choose on the map by clicking on it. For easyer and more accurate selection of you meassuring points, you may zoom in and out, or pan the map.
Of course you are able to save all the prduces graphics. You just have to right-click on them an choose "Save as...". If you want to use the images as input for other models (e.g. RayMan) you have to disable "Include Overlays" in the appearing menu.
Calculate continuous SVF or sunshine duration
For calculating the continuous sky view factor (SVF), you may at first select your area of interest. You can do so by clicking "AIO" button in the navigation menu and drag a box around your investigation site.
Now click "Calculate area SVF". In the appearing menu you are able to set camera hight, the type of SVF ans Sunshine duration, fail value, and a Filename for the results.