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Unread 16-10-2014, 04:58
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Re: Optimal board for vision processing

Quote:
Originally Posted by Jared Russell View Post
...
Basically this advice produces a color depth and image content reduction. The end result of this advice is that the settings will effectively remove large portions of the video image before the video is sent. Reducing the bandwidth required to send the video over the field network. Using the retroreflective tape with a light source would make this easier because the high brightness to the camera sensor will make it survive the process of reducing the camera output. Not sure if this advice will really work out so well if the goal is to track things that are not retroreflective.

A similar concept to reducing the frame rate and/or video resolution and increasing the compression all of which make the video detail less and less useful to human eyes.

All of these options reduce the bandwidth required to send the video in the end. So whether the video is sent with TCP or UDP is less important. Even if TCP sends the video poorly there is just less of it to send.

So I would wonder, with this being the compromise, if the driver's trying to see the video on the driver's station (for example if the vision software was in doubt) would be nearly as useful as just using a targeting laser/light to illuminate the target visually to the drivers and just not using the video at all.

In years before FIRST started using QOS and prioritizing traffic (before the Einstein that caused the uproar) just sending video could put you in a situation where someone on the network might get robbed of FMS packets. We can only assume as teams that the bandwidth controls we have now actually will allow 2-4Mb of video without disruption. Since I know for sure that timing out the FMS packets will stop the robot till FMS can deliver a packet this is a real balancing act.

One of the most concerning things to me personally: is when you are faced with a situation like I was last year where someone that worked on the Einstein issue is having trouble sending video with the expectations that they should have based on the results of that work. Yet they are finding basically that they have less bandwidth than they might expect. So in cases like these I point out that FIRST fields are very dynamic and things might change without notice. So what was without issue on the field network in 2012 might have issues in 2015. It really depends on settings you can neither control nor see in this environment until you have access to that field. I believe there is generally bandwidth to send some video from the robot to the driver's station even using TCP, but you will have to make compromises and they might not be compromises you'd like to make. Hence, at least to me personally, if you can avoid putting that burden on the field by sending video over the WiFi you just should. It will just be one less variable to change on you from your test environment to the competition field.

Last edited by techhelpbb : 16-10-2014 at 05:53.
 


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