CompuServe Messages

George: The following are some things I have learned/deduced/cobbled together regarding the use of the Yost IPAS Boutique's TEMPO routine for creating architectural walkthrus (or drivebys). I make no guarantees that anything I say here is correct, as my usual method is to promptly forget everything I've learned after finishing a project, so that I have to re-learn it all over again the next time….<G> I hope this is semi-cogent — I found myself bouncing around, making corrections and clarifications — so it may be a complete load of garbage! Anyone who wants to straighten me out on anything — please *DO*. The worst thing about planning movement is that every decision you make can pretty much change everything else. So after any bit where a decision is made in all the stuff below, just remember that you may have to juggle back and forth between Tempo & KF and your notes to make adjustments to when and where things are occuring. Without going through a complete case, step by step, it seems virtually impossible to me, to thoroughly write a generic instruction set that you can plug into any situation. In the end, it all comes down to the balancing of three variables: speed of camera movement, area covered (importance of specific start & end points) and overall anmimation length. Which is most important to you? I always seem to find that no matter how slow I make the movement, I'm always told "slower, slower" by the powers that be.<g> I've used about 10mph for exterior "drive-by's", and as low as 2.5mph for interior "walk-thru's", esp in tight spaces. This will take some experimentation on your part, to come up w/ something that feels comfortable — and will likely be influenced by the focal length of lens you use, and even the vertical angle at which you're pointing (as non-level cameras make 3-pt perspectives that, in interior spaces especially, can cause unwanted distortions [which coupled w/ fast movements mean "grab the barf bag"]). To balance the above items, you'll just have to start out with _something_, and modify it as you go along. I find it best to create two dummies (or three, if you require rotations on two axis). To the first, attach the camera and camera-target. To the second, attach the first dummy. Use the first dummy for rotation, and the second for movement along the path. This, in my opinion, _greatly_ simplifies working out rotations w/o disturbing the other movement. After you estimate a total time & create the frames in the KF (again, you'll just have to start w/ a guess based on your knowledge of approximate distance to be covered and target speed), unless you have some strict time requirement that will dictate the speed and path start/stops), start with creating the desired path for the second dummy, without regard to vertice location (ie don't worry about how verts will affect movement — just how they'll affect path shape). Use KEYMAN to embed the original path into the dummy. Open Tempo and select the second dummy, and make sure the settings are for position. Select the "Velocity" graph type. Hit the "Constant Velocity…" button. This will tell you what the constant velocity will be for the path you have created, based on the number of frames you've set in the KF. It's always better, of course, to _over_ estimate the number of frames required. Now, you'll have to play give-and-take w/ those three variables (speed, start and end points, and time). Say you decide on 10mph, as a "constant" speed. Take out a piece of graph paper and make your own version of Tempo's velocity curve. Establish an arbitrary 0mph and 10mph on the vertical, and some arbitrary frame interval horizontally. (This hand-graphing method is of more use when the overall graph gets more complicated, such as if you're going to be slowing down in some areas, or stopping and pausing at various points in the animation.) Perhaps you want to accelerate from 0mph at the animation's beginning, over 2 seconds (60 frames) continue at a constant speed (10mph) and then decelerate over 2 seconds to come to a stop at the animation's end. (Remember, if Tempo told you that based on your path & frame count that your constant velocity was 10mph, by adding an accel from 0 at the start and decel to 0 at the end, you're going to stop short of the end of your path — so you'll either need to increase the speed during the the middle section [the "constant" velocity part], or add frames to the the middle section [thus increasing total number of frames] in order to reach the end of the path on the desired frame.) Assuming that the total frame count is 900 frames, draw a perfectly horizontal line from frame 61 to frame 840. (I'm assuming that we're not using frame 0 as a part of the animation.) Then make a curve from 0mph at frame 1 to 10mph at frame 61. Make a mirror of that curve from frame 840 to 900. Now that you know what your curve should look like (roughly), go back to Tempo and open the Velocity Curve Editor. Reset it and begin constructing a curve that contains vertices at the same frames as in the hand-drawn curve (frames 1, 61, 840 & 899 [not 900 as there is no velocity on the final frame]). Use the "Adjust" button to adjust the tension of the spline segment at frame 61 & frame 840 to get curves. (An accel curve would best start shallow and get steep at the the end, while a decel curve would do the opposite.) If speed isn't your prime concern, check the "fit to track on exit" check box. This will increase the speed during the flat portion of the curve in order to match the end position on the original path. If you don't want the speed to change, embed the spline and exit Tempo. Increase the total frames in the KF and then play w/ sliding the frame numbers for the beginning of deceleration and final stop to the right. Apply, and check the preview. As far as I can tell, playing like this is the only way to determine the number of frames to add to achieve the goal of maintaining speed and position at the expense of total time (frames). After you get something you're happy with, and apply it, you will want to think about whether you need to alter the TCB settings for the keys. If you're doing som pauses, you may want to alter the BIAS to 0 at the first key of the pause, and to 50 at the end to avoid any anticipatory movement. Just make sure to apply these changes AFTER Tempo, else you'll lose them and have to re-apply them. That's the majority I can think of off the top of my head, and from a few notes I wrote myself. Again, I would not be at all surprised to find that some of my assumptions are erroneous — and I may have misremembered a thing or two — so I invite any and all comment. Dave PS Redo both the tutorials — they helped me plenty! PPS After rereading Jonas' post to you while getting ready to post this, I realize I don't really know that much about it at all…. I think I see some things in there that will solve some of the questions I came up w/ just while writing _this_!