AGI32-Calculation Methods
Now that we have a basic understanding of the layout and organization of the program, let's discuss modes of operation and some basic premises in working with different types of lighting projects.
The AGi32 software can be operated using two different calculation methods. The selection of the appropriate method is an important topic that should be clearly understood from your first calculation as they are intended for entirely different purposes. The two different methods are titled “Direct Only Method” and “Full Radiosity Method”. They are selected from the Calculate menu shown below.
This mode computes the Direct component of light arriving at any calculation point in space. Direct Only Method does not consider any interreflections. It does, however, consider the shadowing effect of 3-dimensional objects. What does this mean exactly? It means Direct Only Method will not calculate light that has hit one surface and bounced off toward another. It is therefore not a proper vehicle for the computation of indirect illumination for example. Direct Only Method considers light intercepted by a surface to stop at that surface, it is not reflected.
For what sort of applications is Direct Only Method appropriate? Direct Only Method is designed to compute Illuminance for exterior site lighting, sports lighting, flood lighting and road lighting. It will consider objects as obstructions (shadow casting) and offers several time-saving features to shorten the already very fast computation time (AutoCalc for example).
When the software is set in Directly Only mode the button will reflect that icon (as seen in the menu above). This provides visual recognition of calculation mode setting at a glance.
Full Radiosity Method
The Full Radiosity Method enables all the features found in AGi32 for the accurate computation of interreflected light. Full Radiosity Method is required for interior lighting applications, indirect lighting, daylighting, and when rendering is desired. Due to the rigorous nature of interreflected lighting calculations, Full Radiosity Method projects will always require additional run time over Direct Only Method projects of the same scale.
Switching between Direct Only and Full Radiosity Method is as simple as a mouse click and can be performed anytime. When a project contains three-dimensional entities (Rooms and/or Objects), switching from Full Radiosity Method to Direct Only Method will change all three-dimensional entities into light blocking surfaces. All color and reflectance properties are ignored in Direct Only mode.
When the software is set to Full Radiosity Method the button will reflect that icon (as seen in the menu above).
Photometric Center Position
With the release of AGi32 version 20 the location of photometric center, the light source position, is identical with Direct and Full Radiosity methods. This was not the case is previous versions. In older software the photometric center position in Direct Only mode was the symbol insertion point. When set to Full radiosity method, the photometric center changed to the center of the luminous box. This difference could cause minor discrepancies in the calculated results between the two methods (all other parameters equal).
With version 20 the error between calculation methods has been eliminated, however, you may now see small difference between files computed in version 20 and earlier versions. Version 20 is more accurate.