Entries Filed Under "BOA Plaza Model"

August 20, 2006

Ambient Occlusion

Filed under 3D, BOA Plaza Model, Maya

Ambient Occlusion (AO) is a trendy shading method for 3D graphics. It is useful for showing off geometric detail. Most AO renders are a single color, usually white, with no texture. AO is a simplification of global illumination (GI). GI can be very time consuming, whereas AO is relatively quick. Here are a bunch of AO examples. Besides simulating the ambient shadows from GI, AO is also used for "rust shaders" and "dust shaders" since AO is darkest in crevices, where rust and dust are the most likely to exist.

I was using Maya 6.0 which did not have built-in support for AO. I was considering creating my own AO shader for Maya 6.0, but decided instead to just upgrade Maya. Now I'm running Maya 7.0 (with 8.0 on the way).

Maya's AO is accessed as a Mental Ray shader. To do an AO render, create an ambient occlusion texture (Maya->Window->Rendering Editors->HyperShade...->Create->Mental Ray Textures->Mib_amb_occlusion) and drag it with the middle mouse button and drop it on the object you want to render. The Connection Editor will pop up to ask you how to connect the Mib_amb_occlusion to the object. Select the "OutValue" of the Mib_amb_occlusion and the "Surface Shader" of the object. When you render, make sure you choose "mental ray" as the renderer to see the results.


Here are some pics of the window I did for the Bank of America Plaza. This picture is from below looking up at the window.






From the side.








I need to place those windows on the building. First I tried duplicating the window with an offset, which was very time consuming and left me thinking there has to be a better way.

Next I found a plug-in in Maya called "geometryPaint." To use geometryPaint, you pick an object to paint with and then use the "Artisan Brush" to paint the geometry on another object. It seems like this would work well, but I ran into a problem. I set the brush to paint my window at every vertex I touch. For interior windows this is fine, but windows on the edge are a problem. The brush uses the normal of the vertex to determine the orientation of the window. The normals for the interior vertices are correct. The normal for vertices on the edge are shared by two sides, so the brush averages the normals. This gives you windows at an angle...which is not what I want.

I could probably just paint the whole model and then go back and rotate the edge window correctly, but I'm going to try another approach...MEL (Maya Embedded Language) scripting.

August 12, 2006

Placing Windows

Filed under 3D, Architecture, BOA Plaza Model, Maya

In the picture above you can see one window (upper center) placed on the building.

I used a lattice (Maya->Animation->Deform->Create Lattice) to make the window fit into the window rectangle on the building. I had some problems when I was trying to snap to vertex since there were so many vertices. I found that I could simplify the scene and then moving the lattice became trivial. I added 4 "locators" (Maya->Create->Locator) and placed them in the 4 corners of the destination of the window. A locator is just a vertex place holder. With the locators in place, I could hide the entire building model and just use the locators. Next, I hid the window geometry and just used the lattice cube. Instead of working with tens of thousands of vertices and struggling to get the right vertex in the right location, I only had to work with 12. MUCH easier and a big time saver.

One window down, thousands more to go. I started using the duplicate command with and offset (Maya->Edit->Duplicate) to position windows. There were two problems with this...it is *very* tedious* to have to type in all the offsets to place a windows and my system started to grind to a halt when I added about 20 floors of windows.

I decided to stop and try a different approach. My new plan to address the placement issue is to use a script plug-in that comes with Maya called "geometryPaint". It sounds like I could describe how windows are spaced on a grid, make the building paintable, and then just scribble on the building until it is covered in windows. There is no documentation for this script as far as I can tell, so I'll need to do some experimenting and digging on the net.

I believe I already have a good solution for the performance issues as I add many windows. In the original window file, I created a 4 vertex plane that represents the window and has the same dimensions as the window. I put both the high resolution window (the original) and the low resolution window (4 vertex plane) in a LOD group (Maya->Edit->Level of Detail->Group). For the LOD group, you can choose to let the distance from the camera determine which model is used or you can set it manually. While I am modeling, I am going to manually set the low resolution window to show. When I am ready to render, I switch it so that the high resolution will show. Since all the windows are "references" (Maya->File->Create Reference....), I should only have to change the LOD group once and it will effect every window on the building model.

July 27, 2006

Window Finished

Filed under 3D, BOA Plaza Model, Maya

I finished up a single window for my model of the Bank Of America Plaza. I used a couple of pictures I took as reference photos (here and here).

Being an engineer...I like to make things perfect. However, I don't have the blueprints for this building, so there is a lot of guess work. That is probably the most difficult part for me...using my best judgement instead of using an exact measurement.

I put *WAY* more detail than I needed, because I want the model to capture subtle shadows in the crevices (between windows, the horizontal indention in the base, the horizontal bar across the window, window indention from frame). It took 47 faces to build, which isn't much. However, this window will be repeated on the building over 13,000 times! That will put me at around 600,000 faces! And I haven't even gotten to doing the ground level or the detail on the roof. I will quickly have to figure out how to work with a very polygon-heavy model!

After I finished the window, I tried to attach it to the shell of the building. I *thought* I would just turn on snap to vertex and then use the scale tool to stretch the window to fit inside one of the open window faces on the BOA shell.

Unfortunately, Maya doesn't work that way. Snap to vertex only snaps when *moving*, not scaling. I could not just move my window because I needed to move *and* shrink the window proportionally to fit in the face of the building. My Maya mentor Kyle Rives had a brain storming session on how to best make the window fit precisely in the face on the shell of the building. There were plenty of ways to do it, but I wanted to do it the "right way"...the most efficient way possible. Kyle came up with the idea to try using the animation menu's "Deform->Create Lattice". I never would have thought to look in the animation menu set for the solution to a modeling problem, but it worked really well. I just put a lattice around my window, turned on snap to vertex, and then moved each corner of the lattice to the face of the building. The lattice took care of scaling the entire window appropriately. I still have more work to do on it, but the lattice tool worked really well and is a big time saver.

I'm off to SIGGRAPH...so no more updates until I get back.

July 8, 2006

Building Downtown

Filed under 3D, BOA Plaza Model, Maya

My buddy Trey (a.k.a. Spaghetti) and I want to get better at 3D modeling. The problem is that 3D modeling is time consuming and it is very easy to let it drop as life gets hectic. That's where the blog comes in. We are both going to detail our work in our blogs. If I don't see a regular update from him on his blog, then I will harass him until he starts producing...and I expect the same out of him.

Peer pressure has already worked...I was supposed to do this initial blog entry last week, but I got tied up with a few things...which triggered the guilt-inducing emails from Trey. It worked!

Trey will keep me honest...but I welcome prodding from anyone. If you notice I'm not updating my blog with 3D modeling updates, send me an email or post a comment...it will definitely help keep me on track!

So what am I going to model? I want to build downtown Dallas. I am starting with the tallest building in Dallas, the Bank of America Plaza.

The Skyscraper Page is one of my favorite websites for looking up information about tall buildings. Here is their info on BOA Plaza.

I am going to use Maya 6.0 for modeling. We use Maya at work, so anything I learn on this project helps me with my job as well. I use a SpaceBall 5000 to make manipulating 3d models easier (left hand on SpaceBall, right hand on mouse). For manipulating images, I'm using Corel's Paint Shop Pro X.

Here is what I have so far. I built the frame of the building. Next up: add the windows.

All of my updates will be filed under the BOA Plaza Model category. Spaghetti's updates are here.


Apparently my Xbox 360 has a lot to say. Read its blog here.

About BOA Plaza Model

This page contains an archive of all entries posted to David's Blog in the BOA Plaza Model category. They are listed from oldest to newest.

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