Overview of Lighting Analysis
in 3ds Max Design 2009

3ds Max Design 2009 contains exposure simulation technology which can be used to obtain data on light intensity in your design. This data can facilitate the evaluation of indoor environmental quality required, for example, for LEED 8.1 certification. Ill attempt to explain the basics of how the workflow on this new functionality here.

Normally, you would perform light analysis at the beginning of a project, so for my examples, Ill be using a scene that does not include any materials except glazing on the objects. You can (and probably should in some cases) perform this analysis after some materials have been applied especially those with reflective qualities. When using materials, a valid analysis requires materials to be physically correct such as ProMaterials or mr architectural design materials.

In this first scenario, I want to analyze the lighting quality in the upstairs loft to determine the amount of artificial lighting needed during the daytime hours. The lighting source in this scene consists solely of the mr sun and sky daylight system (see figure below)

First step is to open the lighting analysis assistant. Go to the lighting tab in the assistant and see that the scenes light sources have already been located and added to the list. Select the daylight system and open the modifier panel. Max Design 2009 contains some new sky models for the mr Sky light: Perez All-Weather and CIE. In this particular case, were going to change from the default haze driven model of the mr daylight system to the Perez model (Daylight Parameters> mr Sky parameters) and then enable weather data file (Daylight Parameters>Position). Click the setup button and select load a weather data file. (See figure below)

Free weather data files are available to download from http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data.cfm.  Most of these files are based on older weather dates, but there are some newer data files available also. Ill load one in my scene for Boston. Then at the next screen, you can select a specific time and date or you can select a range of dates to analyze. In this case, Im changing the date to June 22 at 9 a.m.

Next we need to select a method to analyze the data. Well talk about the two different methods. The first one is using a light meter to analyze the lighting data in a specific location. On the Lighting Analysis Assistant, select the Analysis Output tab. Ill click on create a light meter and place a light meter helper in the loft area. With the light meter helper still active, Ill change the number of segments in the modifier panel from the default of 3 to 7 each to give me more lighting analysis figures. (see figure below)

In the Lighting Assistant, click on Calculate all Light Meters Now. The result of the analysis will be placed on the light meter helper. If you need to export the analysis data to a file, you would do so by clicking on the Batch Export Light Meter Data to File(s) button on the Analysis Output tab. To visually see a better range of color on the meter, go to the General Tab of the Lighting Analysis Tool and change the maximum lux to 2000 instead of the default of 10000 (Analysis Value Color Coding). (See figure below)

The other lighting analysis output option is to do an image overlay. To activate an image overlay, select create image overlay effect (located near the bottom of the Analysis Output tab). This brings up the exposure control dialog box. Highlight the effect and then make sure you have Show Numbers on Entire Image enabled in the Display Options below. (See figure below).

Click on Render and render the analysis. The image overlay will be overlaid on the render and can then be saved as a visual image or the output can also be output to a file as mentioned earlier. The Image Overlay effect also displays an additional rendered frame (mostly yellow) that shows a pseudo-color-like display. The appearance of this frame is unimportant: it is simply an aid to calculating the overlay effect, and can be discarded. See images below.

Discard the render below

Based on this feedback, Id consider adding a blind to the windows with some transparency and then calculate this again.

So why would someone want to analyze the lighting in a scene? One of the main reasons (other than for LEED certification) would be to determine if my design contained lighting interferences, either in human interaction or with signage or display. It can also help with determining thermal/cooling costs and artificial lighting costs.

I hope this helps guide you through this new feature.

Submitted by Joy Voltenburg, Multimedia Consultant and Autodesk Certified Instructor - 3ds Max, Hagerman & Company, Inc.

October 2008