Camera Slider with target aiming

[octavian]

I'm studying film and am currently trying to build a motorized slider and a gimbal for my camera. Unfortunately I'm not a programmer nor a robotics expert by far and time is of the essence. I can handle node based programming interfaces like flowstone, but I'm not sure if it's capable of what I need to do with it.

The most important feature I'm trying to accomplish is for the camera to look at a static object during a dolly or slider move. Assuming that I manage to connect a motor with an encoder like this one http://www.pololu.com/catalog/product/1442 to flowstone and can controll it with decent accuracy. Camera rotation shouldn't be a problem, I already connected a servo successfully. Now I want to rotate the camera while it's moving, to always look at a specific target. If its rotation angle is simply wired to the encoder position info, it wouldn't work with targets closer than 2m. So it can't rotate at linear speed, it has to accelerate towards the middle (of the slider where it's closest to the target) and slow down toward the ends. Mabe by calculating the angles of the triangle formed by starting point, end point and target, to speed up camera rotation for the middle where the line between camera and it's target makes a 90° angle.

I have yet to explore flowstones possibilities, but I need a shortut. If I get it to work with flowstone I'll stick with it.

[Embedded]

For sure FlowStone can easily do this, but it's no two minute programming task!

How do you propose to identify the target to be tracked?

One solution would be to use a separate webcam as the eyes as this can quickly be integrated into FlowStone. Also if you need a smooth non linear transition you will need to use a PID algorithm:

http://www.dsprobotics.com/support/viewtopic.php?f=11&t=32

One example with a few of the things you are talking about is here:

http://www.dsprobotics.com/support/viewtopic.php?f=11&t=140

This has motion detection, webcam, targeting colour recognition etc.

There is also a face recognition example that give you the coordinates of a face, might help:

http://www.dsprobotics.com/support/viewtopic.php?f=11&t=100

I hope this helps?

[octavian]

Yeah thanks for the PID, that's certainly a piece of the puzzle.

I was thinking about face recognition and so on, but dismissed it, assuming it would have a notable latency. I thought it would be easier to come up with a math formula or something to calculate the angles of a virtual triangle. Like flowstone would pretend there is a target and it's making an object face it like target cameras in 3D Studio Max.

The end result should be an adjustable distance parameter. I would just have to meassure the actual distance between the camera and the objekt, then feed that info to flowstone manually. One reason I need this is for lack of curved dolly tracks. For realtime shots one could exercise tracking an objekt during a dolly slide, but not for timelapse shots.

Another effect is a little more complicated. I'm trying to achieve a kind of motion blur wich is frozen in space and the camera moves around it or through it. that can be achieved by long exposure. Every image is one slide of the camera. It looks like a photo taken from a driving car at night. But I want to put that slider on a slow moving dolly and Move it in a right angle to the slider direction. Then it seems like the camera is moving through the motion blur of another camera. The problem is though, with motion blur you don't see Objects or People getting closer. Due to the Parallax effekt stuff in the background doesn't pass by as fast as things in the foreground, thus being less blurred. But if the camera aims continously at an objekt...it would be in focus and crisp. It's simmilar to depth of field but awesome!

[Embedded]

So basically some for of IK.

One quick way to get the results right are to simulate it first in graphics and then connect it to the hardware.

Here's an example using IK for a hexapod, buy graphically simulating the problem:

http://www.dsprobotics.com/support/viewtopic.php?f=63&t=382

[octavian]

Thanks for the help, that seems to be the right direction. Unfortunately for me it's to much programming (as in hacking on your keyboard instead of wiring). Don't know if I'll be able to figure out how to build this.

What I need in the long run is a software with a timeline and keyframes animation (beziér curves), to quickly set up animations for the servos on set. I found something promising, but it's actually crap: http://www.brookshiresoftware.com/vsa_overview.htm
The interface is horrible and it doesn't have acceleration curves, so you can't animate precisely. I'm a professional 3D animator with 3Ds Max. But I don't think there's anything with a similar interface for servos out there. I'll keep looking, Flowstone is still the best solution so far, if I'll be able to learn it.

[DSP]

I have been working on a similar project with DSPRobotics for animating a robot arm. This has a new sequencer that DSPR has made in Ruby, it has a time line and you can edit the key frames etc. it will be perfect for your a application.

It's not quite finished yet but it should be done in a few days:

Ruby FlowArm3-05.jpg (58.27 KiB) Viewed 23002 times

Once it's done it will be posted in the examples area for all.