3ds Max and Revit Interoperability - Part 16 - Animating Cars
In this tutorial, you animate cars and buses using simple keyframing techniques and path constraints.
- Recorded in: 3ds Max 2015
- This tutorial is intended for use with 3ds Max version 2015 or higher.
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With a set of cars ready to be merged, open the museum file you worked on last. You can also use the file named Museum_cars.max
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Using Import > Merge, merge the mycars.max file you have just saved.
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Move the vehicles closer to the front of the museum building. This is the main intersection you will be rendering.
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There are many ways to animate vehicles. Short of using a traffic simulation plugin, the most common way is to constrain a car to a path.
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If the motion is simple such as going from point A to point B in a straight line, you can also keyframe the position.
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For example, let's say the bus is moving along this street before it stops at the red light.
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In fact, there is a bus stop at this corner hidden from view at this time.
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Before you animate the bus, consider your timeline.
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The animation length is set to 100 frames by default. That's about tree seconds using an NTSC signal of 30fps.
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You'll need to extend that to about 20 seconds or 600 frames.
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This is done in the Time Configuration dialog.
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Next, you animate the bus by moving it along its road lane.
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To animate the motion, ensure Auto Key mode is enabled.
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Go to frame 300 and then move the bus towards the intersection.
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Play the animation, the bus moves and stops at frame 300,
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and is immobile for the remainder of the animation.
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However, the motion of the bus seems to be accelerating in the beginning and decelerating at the end.
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Deceleration is good, as the bus is braking to a stop.
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However, given its starting position, we have to assume it's already moving at a constant speed.
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To adjust the speed and timing, right-click the selected bus and go to the Curve Editor.
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In this particular case, you are interested in the Y-axis, displaying the motion of the bus.
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Notice the curve, how it starts and ends in a shallow mode to become more pronounced in the middle.
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Select the first key (beginning of the animation) and adjust the tangent to get a linear speed at the beginning and a deceleration at the end.
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If you feel the bus is moving too slowly, then you can adjust the timing.
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If the bus needs a shorter time to reach its destination, then change the end key to finish earlier, somewhere between frames 200 or 250.
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Adjust the curves accordingly and exit the Curve Editor and Auto Key mode when done.
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Playback the animation.
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Go back to Frame 0 when done.
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As mentioned earlier, while keyframing works well in certain simple situations, it is common to constrain moving vehicles to paths.
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This is done by first drawing a path using the Line tool.
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Make sure it's set to Corner/Corner modes as a starting point. You can modify that later.
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Draw a line along this road lane. Hold Shift to use Ortho mode.
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Select one of the cars you imported and then use Animation > Constraints > Path Constraint and then click the line you drew.
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Two things happen: the car is relocated to the beginning of the path and is now animated to travel along the path.
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You still need to adjust it though.
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Zoom in on it and notice it's pointing the wrong way.
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In the Motion Panel, set it to "Follow" the path. If anything, it's even worse. You still need to set the travel axis correctly.
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Try all three,
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the Y-axis seems to work best but it needs to be flipped.
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Play the animation,
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the motion seems a little slow, even for a safe driver.
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There are a couple of things you can do: First, you can extend or shorten the path by moving its vertices.
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Second and most importantly, you can adjust the timing.
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With the car selected, go to the Curve Editor.
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Unlike earlier where you were dealing with position axes, here you are dealing with a "Percent" track.
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This track is effectively telling you that the car is at 0% of path travel at the beginning of the animation,
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and at 100% of path travel at the end of the animation at frame 600.
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In this case, you want the car to reach the intersection earlier, as you did with the bus.
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Select the second keyframe and change it from frame 600 to 200. The car is now reaching the intersection quite a bit earlier.
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However, two things remain: it's slightly overshooting the stop line and it's stopping abruptly.
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Past frame 200, the car is at the end of the path or 100% of path travel.
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At 100%, the car's front is overshooting the mark. Reduce the Percent value so that the car doesn't annoy pedestrians crossing the street.
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In my case, a value of 97% seems about right.
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Looking at the animation curve, it's obviously linear and there are no tangents to adjust speed.
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This is because the Percent track is set to a Linear Controller by default.
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You can change that by switching it to a Bezier Controller. This is done by first selecting the track, and then assigning a Controller with a right-click.
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This will let you adjust the curve and the speed of the vehicle.
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Test the animation.
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Let's try another, more complex one, with a path that turns a corner.
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Draw an L-shaped line using Shift for Ortho mode.
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In the Modify panel, use the Fillet command to round off the corner vertex.
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You can obviously use another car that you merged, but ultimately, you will need to duplicate a vehicle you have already animated.
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You can do that by selecting an animated car and press CTRL+V.
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Choose Instance and press OK, and then go to the Motion Panel.
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Currently, the duplicate follows the original, being constrained to the same path.
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In the Motion panel, click on Delete Path to remove that constraint.
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Use Add Path to relocate the duplicated car to the new path.
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Click Add path again to exit that mode.
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The car is now constrained to the new path but its speed needs adjusting. It needs to slow down for the right turn.
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Scrub the animation and take note of the path travel: The car reaches the intersection at about path %: 44
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This may be different on your system based on how you drew the line, take note of that value.
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The car should decelerate reaching this percentage of path travel.
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It should then move at a constant slow speed around the bend, until it reaches path %: 56 and then accelerate out of the corner.
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In the Curve Editor, use the Add Keys button to add two keyframes to that curve.
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Using Move Keys again, select the first added key, (the second on the curve) and set its value to 44, where the car reaches the intersection.
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Now select the second inserted key (the third on the curve) and set its value to 56 marking the car exiting the turn.
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Ultimately, you have to adjust the timing and the tangents until the animation feels right.
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If you have time, animate more cars and buses to your city environment.
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In the next movie, you'll use a version of the city with a few more animated vehicles and create animated cameras.