Category Archives: VI-Suite

VI-Suite v0.4 – Version 0.4.12

Posted on by
1

I have just released version 0.4.12 of the VI-Suite. Minor changes this time but there was a nasty bug when setting an air layer in an EnergyPlus wall construction and I felt the fix deserved a new release. As part of fixing this bug I introduced a tiny new feature which is to display an indicative U-values in the ‘Material’ tab for exported material associated with layer 2 EnVi geometry. This indicative U-value assumes the material is on an external surface and uses internal and external surface resistances of 0.12 and 0.08 m²K/W respectively.

There is also a new option in the LiVi Geometry node called ‘Fallback’. Turning this on makes LiVi export a pure polygon Radiance geometry description. This is more reliable and is indeed faster to simulate in simple cases but will ignore any specified smooth shading,  textures or normal maps.

VI-Suite v0.4 – Version 0.4.11 & Sky View Factor Calculation

Posted on by
Reply

Version 0.4.11 has now been released. This version contains a number of bug fixes and new features,  including the ability to create a sun path with hourly or monthly suns and a new Sky View Factor node. A zip file containing the VI-Suite addon for Blender version 2.7.8 has also been released for Linux 64bit systems. See the changelog page for more details.

The sky view factor (or VI SVF) node operates in a similar manner to the Shadow Map node except that instead of checking if a point can be seen from the perspective of simulated sun positions it is checked if it can be seen from different portions of the sky. The sky can be subdivided into 145 portions (Tregenza) 577 portions (Reinhart 577) or 2305 portions (Reinhart 2305). Accuracy and simulation time increases with each one.

The VI Sky View Factor node can be added through the ‘Analysis Nodes’ menu. An image of the node is shown below. Options are similar as for the Shadow Map node except there is no location input required and no time options, as sky view factor is location and time independent. The ‘Results Out’ socket can be used to save the results to CSV file.

SVF Node

Sky View Factor Node

An example analysis with a 3D city model of the Hague in the Netherlands can be seen below.

SVF analysis

Sky View Factor analysis of the Hague. Model provided courtesy of Filip Biljecki.

 

VI-Suite v0.4 – Radiance Textures

Posted on by
Reply
Normal mapping

Radiance render with multiple normal maps

This tutorial is basically a follow up to the Radiance Patterns tutorial and details how normal maps can be used to specify Radiance textures. Textures in Radiance terminology is a perturbation to the surface normal to give the impression that the surface has detailed physical features. If for example a point on a surface has its normal perturbed towards a light source the point will receive more light than if the surface normal is perturbed away.

Although, like Radiance patterns, textures are not often necessary for numerical lighting simulation, and indeed are ignored if they are on an illuminance sensing surface, they can provide extra realism to visual Radiance renders and there are certain circumstances where they may be useful numerically and/or save time by not requiring the creation of detailed physical geometry.

The video below details the process.

VI-Suite v0.4 – Artificial Lighting Simulation

Posted on by
Reply
Lighting simulation of Blender's classroom scene

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.

VI-Suite v0.4.10 & Esri Grid import

Posted on by
Reply

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.

Brighton shadow map

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.

Esri Grid visualisation

Material node set-up for Esri Grid data visualisation

An example colour visualisation of annual rainfall in Africa is shown below.

Rainfall in Sub-Saharan Africa

VI-Suite v0.4 – Radiance Patterns

Posted on by
Reply

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.

The video tutorial below details the process.

VI-Suite v0.4 – Radiance Photon Mapping

Posted on by
Reply

Hello.

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.

Video below.

 

VI-Suite v0.4 – Importing Geometry

Posted on by
Reply

Hello.

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.