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ecotec Import DXF
Adding Cameras
Adding Lamps
Using IES Data
Import DXF
To import an dxf file, go to File->Import 3D CAD Geometry. Make sure the units are correct.

Since luminance is viewpoint dependent, you'd need to specify a camera to setup view points. The first mouse click (or x-y-z numerical input) specifies the location of the camera, the second click (or x-y-z numerical input) specifies the direction of camera view. Note that the default camera is a 90-degree wideangle camera. To change camera settings, you change the material of the camera. While this is counter-intuitive, think of it this way: the camera object, like any other Ecotect object, describes its geometric location and direction. The characteristics of the object itself (thermal and lighting properties for surfaces, or in this case, angles and clipping distances of the camera) is captured in it's material. The name of the material is simply that, a name. Obviously, if you have 2 wideangle cameras but different angles, say 90-degrees and 100-degrees, you'd create 2 different materials, and assign them to the 2 cameras correspondingly.

The view-fustrum of the cameras are indicated in the 3D-Editor and also appear as shortcuts in the Visualize tab.

If you're adding simple lamps or axially symmetrical lamps, the help files will be sufficient. A point to note is that lamp characteristics are modified via it's "material". While this is counter-intuitive, think of it this way: the lamp object, like any other Ecotect object, describes it's geometric location and direction. The characteristic of the object itself (how much light a surface reflects, or in this case, how much light a lamp puts out) is described by it's material. Obviously, if multiple lamps of similar types but varying lumen output are used, the material has to be duplicated; one for each type.

The polar curve of each lamp can be specified via the Output Profile tab in the material. Note that the polar curve is limited to axially symmetrical conditions, direction of lamp to the right. Also, instead of specifying the luminous intensity in each direct, you use ratios normalized on a scale of 0 to 1. The polar curve for a FlouroRecessedDroppedDiffuser lamp (above) is show below.

Consider that we'd like to add a simple spolight for the sculpture. First, let's take a look at the original setup (at 5pm). The view in Ecotect (Visualize) is as right:

We'd use Radiance to produce a luminance image. Go to Analysis Grid, add a grid, and Perform Calculation. Select "Export to Radiance for More Detailed Analysis -> Luminance Image -> Final Render -> Cloudy Winter Sky (depending on design scenario) -> Use Current Date and Time -> Interior Side -> Medium Model Detail, High Lighting Variability and High Image Quality.

As expected, the scene appears washed out (no lamps, little daylight at this time).

To add a spotlight, click on the Lamp button. The first click (or x-y-z numerical input) specifies the location of the lamp, the second click (or x-y-z numerical input) sets the direction vector of the lamp. In this case, the material of the lamp is modified to specify a 3000lm lamp, with 40-degree hotspot and and 50-degree cutoff.

Using Radiance again, the following (luminance) image is generated.

Using IES Data

Assuming we'd like to use non-axially symmetrical lamps, and we have the polar curve defined as an IES file. While this is not possible in Ecotect, Radiance does support such a feature. This means that you'd have to prepare all information, geometry, material definitions, IES data, in the Radiance format, which is a pain. Fortunately, most of the Radiance input files prepared by Ecotect are still correct; we'd just have to add IES data, and point the lamp to this new data.

Without going into details, you'd have to (minimally) do 3 things.
* Process .ies files (polar curves) into Radiance format
* Get the Radiance files prepared by Ecotect
* Modify the Radiance files to link to your (processed) IES files

Process .ies files

IES files are IESNA formatted photometric data; essentially describing the lamp intensity polar curves. They are usually provided by manufacturers; we're using ERCO's T12 fluorescent lamp. A copy of the IES file is here. To process this file into the Radiance format, use the ies2rad utility. Open the command line and type ies2rad -dm filename.ies. -dm specifies an ies file in meters, -di when the file is in inches. Check this by opeing the ies file in a text editor.

Get the Radiance files prepared by Ecotect

Do the usual Perform Calculation Select "Export to Radiance for More Detailed Analysis -> Luminance Image -> blah, blah... and make sure the files are saved in the same directory as the ies.rad and ies.dat files.

Link to your (processed) IES files

Open the *.rad file that Ecotect generated. This file contains the descriptions of all geometry objects as well as material objects. Light objects are usually found towards the bottom. In this case, (see file compare picture above), the last 3 objects of my Ecotect-generated rad file describe the fluorescent lamp I drew in Ecotect.

The last object (lines 17086-17092) is the lamp geometry, the cylinder (from line) that I inserted. The 2nd last object (lines 17080-17083) is the material FluoroLampStripUnit. Notice how the lamp geometry object refers to this object. The 3rd last object (lines 17074-17077) is a distribution function FluoroLampStripUnit_dist which essentially describes the polar curve and links to a light095.dat file. Again, the material object links to this distribution function object.

To use your own IES data, open the ies.rad that you generated using ies2rad. You will also see 3 objects in this file (after all the comments denoted by #). The last is of no use to us. Copy the distribution function and material objects to the Ecotect-generated *.rad file. Replace the original material reference of the lamp-geometry object with the one you just brought in. (See picture above, FluoroLampStripUnit_dist is replaced by erco_light.

That's it, run the *.bat file and sit back, relax.

Original Radiance rendering (left) as prepared by Ecotect, updated IES data (right)

Updated 19 August 2008, YC Huang.
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