Radiance visual and falsecolour rendering of Blender’s classroom scene
The VI-Suite can simulate artificial as well as natural lighting. Three main methods are available:
Specifying a Radiance light material to mesh elements.
Associating an IES file with a Blender lamp.
Associating an IES file with a Blender mesh plane to create an array of lights.
IES files, which are text files describing the brightness of a lamp or luminaire from different viewing angles, are released by manufacturers for their specific lighting products and can usually be downloaded from their websites. This gives the opportunity to see how real world products will illuminate a scene visually and with the VI-Suite numerically.
As ever, the video below describes these three methods.
I have just released version 0.4.10, which mostly has changes to the Esri Grid import node (ASC node). Esri Grid is a common geospatial data format.
I have removed the split mesh option from the ASC node as this is now turned on by default. This reduces memory consumption during import, and the user can join the meshes together after import if desired. The image below shows an annual shadow map on an imported 12,000,000 sensor point Esri Grid terrain map. This was done on a machine with 8Gb of ram, and would not have been possible with split mesh turned off.
20x15km shadow map of the coast around Brighton at 5m resolution
I have also added an option to deal with invalid data in the Esri Grid file. These points can now be zeroed or deleted from the imported mash.
Esri grid files do not necessarily contain terrain height data but can include instead other geospatial data types; rainfall for example. If you want to colour the imported mesh based on these data values you can use the material node set-up below.
Material node set-up for Esri Grid data visualisation
An example colour visualisation of annual rainfall in Africa is shown below.
As of version 0.4.7 the VI-Suite can now use Blender’s UV image mapping system to create image based Radiance patterns. In the example Radiance rendering below an image texture has been mapped to the wall and picture to create a diffuse reflecting Radiance image pattern, and to the window to create a transparent one.
Radiance geometric and sky text descriptions can be accessed, edited and exported via the ‘VI Text Edit’ node. Radiance results can be exported in comma separated CSV format with the ‘VI CSV Export’ node.
The short video below shows how to use these two nodes.
Blender has very good animation capabilities and the VI-Suite uses this animation system to allow time and/or geometry based parametric analysis with Radiance.
The video below demonstrates how to enable a time and mesh geometry based parametric lighting analysis.
Radiance’s Photon Mapping capability can really help a backwards raytracer like Radiance achieve good results in situations where it is difficult for backwards rays fired from the camera or sensor point to find a light source e.g. interior scenes with small windows or small artificial lights.
The video below shows how to turn on and use photon mapping in the VI-Suite. The current implementation in the VI-Suite only works with natural lighting. When I have it working with artificial lights I’ll update this post.
If you’re doing building modelling outside of Blender and importing the geometry into Blender for analysis with the VI-Suite there are some things to bear in mind, especially if the other application is not a mesh modeller like Blender e.g. Rhino, Sketchup.
If possible export the model from the other application with the unit as metres as Blender will interpret the unit as Blender units which are equivalent to 1m in the VI-Suite. Also make sure that your model is situated appropriately relative to the origin point in the other application. If importing 1 building for example put the building near the origin point before exporting.
For most types of analyses with the VI-Suite exporting the geometry as one OBJ or 3ds object can be useful as it makes manipulation of the geometry in Blender a bit easier. If doing an EnergyPlus simulation with EnVi, exporting an object for each thermal zone you wish to simulate is optimal.
Applications like Rhino and Sketchup also have to convert their native geometry for export to 3ds or OBJ files for import into Blender, and this conversion can lead to very messy mesh geometry. The Blender tools ‘Remove Doubles’ and ‘Limited Dissolve’ can help you clean up this geometry.
The video below shows how to prepare imported geometry in Blender for simulation with the VI-Suite.
Below is a video showing how to conduct a simple lighting analysis with Radiance using the LiVi component of the VI-Suite. A simple analysis allows the prediction of Lux, Daylight Factor, Visible Irradiance and Full Irradiance.
The video below details how to conduct a shadow mapping analysis with the VI-Suite. In this context shadow mapping is the prediction of how often points in space are in direct sunlight when the sun is above the horizon. Simulations with the VI-Suite can be done for any portion of the year and use any mesh geometry within the scene as the calculation points. The example image below shows an annual shadow map, with 4 calculations per hour, using the urban building geometry as the calculation points. One of the advantages of this approach is that once the simulation is complete the results are fully navigable in Blender.
I’ve just updated the VI-Suite to version 0.4.2. This version contains various bug fixes and an update to this version is recommended by downloading the complete zip file from http://arts.brighton.ac.uk/projects/vi-suite/downloads for your operating system.
One user-facing change is that if specifying a custom EPW weather file in the VI-Suite settings the Manual/EPW menu needs to be toggled in the location node to update the weather file list.