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Square pixels for square objects

3D in After Effects By Stephen Schleicher
Like creating After Effects projects using the DV/NSTC preset and a non-square pixel aspect? If you do, you might run into problems when creating 3D using AE solids.

While After Effects does great work in 3D space, remember that a Solid Layer originally begins as a 2D object and takes on the pixel aspect ratio of the composition. Using a non-square pixel aspect means that you get non-square solids. For example, if you create a 100 x 100 pixels solid in After Effects, it is slightly taller than it is wide due to the rectangular pixels it is made of.

If you want to create a 3D box (or even build your own 3D city) using only solids, the non-square pixel aspect will get you in trouble, or at the very least, cause you some headaches.

Lets see this in action.

Create a new composition that is using the DV NTSC preset and set the pixel aspect to D1/DV NSTC (0.9).

Create a New Solid by pressing Command+Y on the Mac, or Control+Y on the PC. Make the solid 100 pixels wide by 100 pixels high. Give the solid a unique color (yellow) and press OK.

Create two more solids the same way, but changing the color for each. In this exercise I used green and red as my other two solids.

In the Timeline, change all of the solid layers to 3D layers and parent the Red and Green solids to the Yellow solid.

Select the Red layer and press the P key to bring up the Position Properties for the layer. Change the position to 0, 50, 50. If an object is parented to another layer, it changes the global AE coordinates to local coordinates. Press the R key to bring up the Rotational Properties for the layer and change the Y-axis orientation to 90.

Select the Green layer and press the P key to bring up the Position Properties for the layer. Change the position to 50, 0, 50. Press the R key to bring up the Rotational Properties and change the X-axis orientation to 90.

You have essentially created three sides of a box. With the Yellow layer selected, press the W key on the keyboard to activate the Rotation (Wotation) Tool and rotate the solid to get a perspective on the box. You should notice sizable gaps and overlap between the solids, even though you have only moved the solids half the distance of their width and height.

If you have spent a great deal of time creating a complex model using only solids, dont fear, you can correct this aspect ratio error by changing the pixel aspect ratio to square pixels.

If you are creating all of the elements of your 3D model in a program like Photoshop, have no fear, the pixel aspect will stay square and you will have no problems building your cube.

Hopefully, this look at why using AE solids to create 3D models in After Effects could cause problems at a non-square pixel aspect ratio will prevent you from having problems in the future.

When not working deep in the labs of the DMN Central Division testing the latest and greatest software/hardware products Stephen Schleicher can be found at the local university teaching a few courses on video and web production. He can be reached at schleicher@mindspring.com. You can also visit him on the web at www.mindspring.com/~schleicher

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Stephen Schleicher is a well known writer, visual effects artist and media guru! You can see more of Stephen at
www.majorspoilers.com and www.stephenschleicher.com
Related Keywords:After Effects, adobe, production bundle, 3d, modeling, square pixels, non-square pixels, schleicher

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