LabView/C++ equally capable?

[Ivan Helmrich]

A while back, there was a thread about autonomous camera tracking.

http://www.chiefdelphi.com/forums/sh...threadid=76991

There seemed to be a consensus forming that teams who had success getting the camera to track well enough used C++ and not LabView. This got me thinking about why this might be and what it means for the future of LabView as a programming option in FRC.

First, was that consensus correct? If so, will we see teams that really want to make the most of their controller abandon LabView or will more effort be put in by the LabView developers to provide comparable capability?

[Jared Russell]

There is a correlation here, but not causation (in my opinion).

C/C++ is a far more universally taught and utilized language than LabView in education and industry (not to mention in FIRST prior to 2009). Thus more programming students and mentors will have a high level of understanding with C++ than with LabView.

The result? More experienced programmers, who are more likely to use C++ as that is where there expertise tends to fall, are more likely to get camera tracking working.

As far as capabilities, be it LabView or C++ (or Java), it all boils down to the same FPGA configuration and assembly language. I don't buy that any FRC language is more or less capable than any other.

[Ivan Helmrich]

Jared, good points. I had considered that it might be a matter of familiarity as you suggest but I would have expected at least some reported success with LabView. I agree that the actual language should not be the limiting factor.

I'm wondering if perhaps the readability of C++ vs. the "black box" nature of LabView has something to do with it. I tried to dig into the LV to see how the video was processed and got pretty discouraged pretty fast.

The question still stands though regardless of cause. Will the correlation drive a change in behavior regarding language selection? I guess my hope is that the video capability provided is adequate in all languages so that a team might concentrate on how to put the data to work controling a robot and not on how to get a basic functionality working.

Ivan

[Jared Russell]

Originally Posted by Ivan Helmrich

I'm wondering if perhaps the readability of C++ vs. the "black box" nature of LabView has something to do with it. I tried to dig into the LV to see how the video was processed and got pretty discouraged pretty fast.

I think this is part of it, too. There is something about engineers that makes us inherently suspicious of black boxes. Sometimes this is a good thing, but it also means that we can be stubborn to accept a good off the shelf solution to a problem. Case in point, you wouldn't believe the number of times a subcontractor on a software project has supplied me with their own implementation of a C++ "vector" class. And as much as I trust that my subs are competent, the odds of them writing a bug-free vector class faster than the Standard Template Library's implementation are very slim.

Originally Posted by Ivan Helmrich

Will the correlation drive a change in behavior regarding language selection?

I believe that in many cases, it already has. Our students learn C++ from experienced programming mentors who know C++. I generally encourage rookie teams to use C++ because if they have a problem, I will know how to help.

[Greg McKaskle]

Originally Posted by Ivan Helmrich

I'm wondering if perhaps the readability of C++ vs. the "black box" nature of LabView has something to do with it. I tried to dig into the LV to see how the video was processed and got pretty discouraged pretty fast.

The vision kernels are in fact a .out file, and are equally black box to all languages, as is the FPGA. If you'd like to ask questions about the LV or C++ image processing, I'll be happy to shine some light on them. I think very quickly, we'll rediscover that there are a few layers of user native language code, and below that you jump into a library. This is the case for all of WPILib.

Greg McKaskle

[Eugene Fang]

Originally Posted by Ivan Helmrich

Jared, good points. I had considered that it might be a matter of familiarity as you suggest but I would have expected at least some reported success with LabView.

Our team (604) used LabView this past year, and we were fairly successful at getting our turret to lock in on our target. We had a potentiometer on the turret, so the camera took a frame, figured out how many degrees right/left to turn, and we used the potentiometer to servo to the position.

We also can shoot in autonomous mode (http://www.youtube.com/watch?v=SmXBMmEgfbI)

However, we do not have any comparison to how fast other robots' turrets center on their target, etc., so I don't know how "successful" we actually were, compared to others.

Here is another video of a test chassis tracking the target with LabView to compare with other teams' speeds. Note that it was only a couple hours of work, so the tuning could have been better.
http://www.youtube.com/watch?v=M84hL57QUvg

[Kaushal.K]

Team 1241 used LV to program in Lunacy. We also were able to get the Camera to track the target, with a fair bit of success at FLR and GTR.

Thanks to Ben Zimmerman and Team 843, without whose teachings and assistance we would be at a great loss, and also to Greg McKaskle and everyone on CD who has provided us with so much help.

[EricH]

Different people prefer different tools and different methods with the same tool to do the same job. If they produce similar-quality work for similar prices, should we care which method they use, all other things being equal?

[rfolea]

Use the tool that is most comfortable for you.

I believe that ALL of the teams that got the camera to work at the Peachtree Regional used Labview.

As a C++ die hard I was reluctant to use Labview. But when I saw how quickly the kids picked it up and how easy it was to teach, and how little trouble we had getting things up and running - I was sold.

We used to spend a LOT of time debugging missing semi colons, etc - so much so the kids would get bored and completely loose the point. Last year the kids were able to program the entire thing themselves with very little adult help. I've never had that experience with text based languages... They enjoyed it so much they even did some side projects.

Very pleased with the whole experience.

We'll be using LV again this year.

[Ivan Helmrich]

Thanks to all who replied, I wasn't looking forward to making a switch to C++ but thought it might be wise given what I read in the thread I referenced. I'll stick with the LV and see if I can get more out of it. Pretty much everything but the camera worked well for us last year so I know where to concentrate my efforts.

[Greg McKaskle]

Your initial question is a reasonable one. I suspect this will be a perennial topic aimed at identifying what will lead to more success, and a particular technology or approach is always an easy difference to gravitate towards -- similar to the wood vs aluminum, six wheels vs four discussions.

To make progress on improving vision, what part of the camera code worked, what didn't? Any questions that you want to ask?

Greg McKaskle

[Ivan Helmrich]

The problems I had with the vision code was frame rate and repeatable performance. Sometimes one color would be picked up, sometimes both. I tried the various changes in values that were suggested in a couple of threads here on CD but never got anything stable enough to rely on.

To be honest, we ended up bailing on trying to use vision for any automation about half way through the build. There were other, non-control issues that needed more attention. I had followed a couple of discussions on the camera but I couldn't dedicate the time to try all of the suggestions. Part of the reason for my original question was that I couldn't find anything in the LV implementation that that would have lead me to some of the methods people seemed to be talking about and so assumed, apparently wrongly, that the C++ code or perhaps comments was more descriptive of the process, less black box like, and that was part of the success some were having.

I was looking for a frame rate somewhere in the 20 fps range. I don't think we got out of single digits. The things I remember reading that should have helped are:
More light
Lower resolution
Turning off some things in the 2 color vi.
There was also some LV specific issue where the code would only process every other frame, I forget the specifics.

The purpose of the thread was to ask the question. If it will be instructive for many of us to change it to a discussion of how to get good camera performance, great. Since many teams are probably starting back up with the new school year, perhaps it is a good time to do this.

So, what really has to change in the 2 color demo to get the frame rate up? Once I can get that working, then I'll work on the reliability.

Thanks,

Ivan

[Eugene Fang]

Originally Posted by Ivan Helmrich

So, what really has to change in the 2 color demo to get the frame rate up? Once I can get that working, then I'll work on the reliability.

Well, the main things we changed were setting the resolution to 160x120 (set in Begin.vi if you're using the advanced framework, i believe) and disabling the "mask display" in the 2 color demo. These two should improve your FPS.

A tip on getting the lighting to work under various lighting conditions:
for the HSL values, define H (hue) as narrow as possible but keep the S and L values relatively wide and set the "brightness" control to automatic (in Begin.vi). That way if the lighting changes you will still be able to track. It's kind of a balance between tracking robustness and picking up extra noise (although the noise sholudnt be that big of an issue because its unlikely that you will have two large blobs of "noise" of green and pink one on top of the other)

During the season we had it set on a fixed brightness and very closely defined HSL values. At SVR it worked great because of the lighting consistency but at Atlanta, the semi-transparent roof cover screwed us up badly.

Hope this helps!