Archive site for Autodesk Ecotect Analysis educational resources, notes and tutorials



Ecotect Tutorial : Radiance Daylight Analysis Part 1

Synopsis

This first of two tutorials explains how to export an Ecotect model to Radiance for daylighting analysis.

Duration

You will need about 25 minutes to complete this tutorial.

Training and Accreditation

Successfully completing this tutorial fulfills one of the practical skills required for completing Level 3 of the Daylight training module.

Resources Required

To complete this tutorial, download and open the RADIANCE_example.eco file found under the Attachments section at the end of this tutorial.

Tutorial


Exporting to Radiance

  1. The example file contains everything you need to be able to perform a daylighting analysis using Radiance. The key elements of this model include at least one zone to be analysed, door and/or window openings to allow natural light to penetrate, and a camera object that allows us to see the interior space of the zone. You can check the camera is position correctly by clicking on the Visualise page, and then clicking the view tab for the camera.
    Use the Visualise and View tabs to check the camera position.
    Use the Visualise and View tabs to check the camera position.
  2. Start the lighting analysis calculation wizard. Go to the Calculate»Lighting Analysis... menu item. Select the Export to RADIANCE for More Detailed Analysis radio option, and then click Next.
    Start the Lighting Calculation wizard, and pick the Export to Radiance option.
    Start the Lighting Calculation wizard, and pick the Export to Radiance option.
  3. Next, specify the kind of Radiance image you would like to create. There are four options - for this tutorial, select the Illuminance Image (Lux) option - this calculates the amount of light falling on each surface, and is suitable for purely analytical purposes, or when the materials and finishes of the interior have not yet been selected (as in the case of this model). Click Next.
    Select the Illuminance Image option.
    Select the Illuminance Image option.
  4. On the screen, select how Radiance should present the generated image. This depends on what you are using the image for - for this tutorial, let's assume you wish to generate a quick image just to see if the natural lighting levels are reasonably correct. Select the Interactive Render radio option, which allows us to see the render in real-time, so we can cancel it and start again if things aren't looking so good. Click Next.
    Select the Illuminance Image option.
    Select the Illuminance Image option.
  5. Next we select what sky condition to use in the Radiance render - this refers to the distribution of light across the sky dome, and is based upon representative sky conditions for different times of the year. As this daylighting analysis is being done on the Summer Solstice in the Southern Hemisphere, select Sunny Sky (Summer) and then click Next. In case you were wondering, these values are based upon the CIE mathematical models for different sky luminance conditions - more info can be found here.
    Blue skies, smiling on me...
    Blue skies, smiling on me...
  6. Now choose what date, time and location to use for the Radiance analysis. This information is generally derived from the settings used in your Ecotect model, as shown in the Date/Time toolbar. For this tutorial, select the Use Current Date and Time option.
    Select the Use Current Date and Time option.
    Select the Use Current Date and Time option.
  7. Next, specify the ambient light levels required and the size of the image to generate. Select Interior Views and choose the 640x480 pixels image size, and then click Next.
    Specify how to calculate the ambient light levels and the image size.
    Specify how to calculate the ambient light levels and the image size.
  8. Choose which views Radiance should render. These are generally based on camera objects you have set up in the model but can also just the view as shown in the 3D Editor. Check the Selected Camera Views and Camera_WideAngle checkboxes, and leave Current 3D Editor View unchecked. Click Next.
    Select the views to render in Radiance.
    Select the views to render in Radiance.
  9. Almost there. Now specify how accurate the Radiance renders should be, based on Model Detail, Lighting Variability and Image Quality. Obviously, the greater the accuracy/quality, the longer it will take to render the image. For our purposes, set all of these to Medium, and then click Next.
    Set the quality to Medium for all.
    Set the quality to Medium for all.
  10. Just need to check that Radiance is installed correctly. If all is good, this dialogue box should look like the following screenshot, and all you need to do is specify where to output the Radiance image (Note: it is advisable that this path location be a short as possible from the root directory, with folder and filenames no more than 8 characters long). If your screen doesn't look like this, you may need to check your Radiance installation - try following this tutorial here.
    If all is good, your screen should look like this.
    If all is good, your screen should look like this.
  11. Last wizard screen! You'll see a summary of all of the settings you have selected using the wizard. Make any changes at this point if necessary, but otherwise click Ok to start the Radiance render.
    Check your selection settings, and then click Ok to proceed.
    Check your selection settings, and then click Ok to proceed.
  12. And it begins! A command prompt window will appear, indicating that Radiance has started the rendering calculations. Another window will also appear, showing the progressive refinement of the rendered image - this is thanks to the Interactive Render option you selected previously.
    Low.

    Low.

    Medium.

    Medium.

    Woohoo!.

    Woohoo!.

    Radiance starts the calculation and rendering process.

    The interactive rendered image should only take a few minutes to complete. If it looks pretty good, repeat the above process, but this time select the Final Render option, and set the quality to HIGH. Naturally, this image will take longer to generate, and should look something like the following image :

    The Radiance render, using the Final render output option.
    The Radiance render, using the Final render output option.

    The next tutorial explains how to overlay analysis information over the top of this final rendered image.


AttachmentSize
RADIANCE_example.zip74.46 KB
Ecotect Tutorial : Importing Radiance Calculation Data
Ecotect Tutorial : Radiance Daylight Analysis Part 2

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error

comment posted by Ulrik_p :: 4 May 2008 - 11:19am

hello

then I follow this great tutorial, and push the "ok" puttom at the end of the wizard then I get this message FATAL ERROR - cannot find function file "rayinit.cal" Does anyone know that I should do?


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