Hey All. My Pratt class ended a few weeks ago and there was one thing that I couldn’t quite get to work in the last class. We were using a daylight system and mental ray physical sky, but wanted to use our own, custom, background image. I promised the students I would research the problem and let them know how to do it. I immediately did some research and found, ironically on a the blog of a friend of mine, the solution. His name is Roger Liucci and his website is Revit Zen at http://revitzen.blogspot.com. Roger gave me permission to write-up his posting so I thank him for that.
First of all, I’m going to assume that you have already added a daylight system and have therefore had 3ds Max automatically insert an mr Physical Sky into the environment map. Once you do this, if you hit render (after adding a plane and box with basic, light-gray materials, and set the time of day to 2pm), it would look like this:
That looks pretty good. If I change the time of day, month, year, geographic location, etc., that background would change accordingly. To change that background to an image of our choice, we need to modify the mr Physical Sky that was placed into the environment map. Here’s how:
1. Click the Rendering pull-down menu and click Environment (you could also have tapped the 8 key on your keyboard).
2. Next, click the Material Editor icon (you could also have tapped the m key on your keyboard).
3. Within the Environment and Effects dialog box, left-click and hold on the ( mr Physical Sky ) button and drag and drop it onto an empty slot within the Material Editor:
4. When the Instance (Copy)… dialog box appears, select Instance and click OK. You select Instance because you want all settings that you change in the Material Editor to have the same settings as the mr Physical Sky within the Environment Map.
5. Select the map you just added to the Material Editor and, when the settings appear below, select the box to the left of the Use Custom Background Map option and then click the None button.
6. When the Material/Map Browser appears, double-click Bitmap.
7. Locate the image file you’d like to use as a background and double-click it.
Roger now writes, “One would think this is all that’s necessary, but it still won’t show up correctly.” He’s absolutely right. If we render it right now, it looks like this:
The next step that Roger wrote was exactly what I had left out when I taught my students (so pay attention):
8. Back within the Environment and Effects dialog box, within the mr Photographic Exposure Control group, underneath where it says Physical Scale, select Unitless and set the value to 100000. If we render it now, it looks like this:
This looks better, but you probably notice that the original horizon is cutting through the image. To get rid of this, follow these steps:
9. Reselect the daylight system and, on the Command Panel, switch to the Modify tab.
10. Scroll down and, within the mr Sky Advanced Paramters group, remove the check next to Aerial Perspective:
This is what it’ll look like if we render it now:
If you find that your image is too large, needs to be cropped or needs to be shifted, return to the bitmap settings within the Material Editor and edit any of the settings highlighted within the following image:
Again, thanks VERY much to Roger Liucci of RevitZen (and by the way, here’s the direct link to his post: http://revitzen.blogspot.com/2009/01/visualization-in-max-takes-practice.html). I hope this was helpful to you all and especially to my four students from the Fall ’09 semester.