Switching between two webcams on the dashboard

[jojoguy10]

Hey Teku14,

We successfully (after 5 hours!) managed to switch webcams. I will post the relevant VI snapshots and try to explain them the best I can. Here is a link to the code we tried and some annotated screenshots.
https://drive.google.com/folderview?...&usp=sha ring

Vision Processing:
We created two cameras (notice the different RefNum names ) and wired them into our new Background Loop VI.

CameraBackground Loop:
We had to create a second RefNum input for the second webcam and run two (2) Send2PC loops (one for each camera).

Send2PC:
It looks like you did the Send2PC perfectly. Just create controls for the port and the image name, and set them as inputs for the VI.

DASHBOARD:
DashboardMain:
We had to do a bit of trial and error to get this to work correctly. We have a bit of code (highlighted in the orange box) that would "refresh" the feed and the port. Without that code, we would flip the camera switcher, but the image wouldn't update with the new camera unless we switch from Camera HW to Camera SW (or vice versa). So, this little block of code automatically switches from HW to SW (or vice versa) if the port changes.

CameraRead_MJPG:
This was a tricky VI because it was a clone and you can't edit a clone. The trick I found to edit a VI is:

• In the DashboardMain VI, do a CTRL+F (find)
• Next, under "Select Object", click the "Add" button and go to: Objects in vi.lib and if you scroll all the way down, you will see the Camera VIs
• Find the Dashbd MJPG VI and left-click on it
• Next, in the "search Scope", choose the "<All VIs in Application Instance>" and make sure the "Hierarchy Window" checkbox is checked
• Flick Find
• Double-click on "VI Hierarchy"
• You should be able to click and drag the VI (Dashbg MJPG) into the Dashboard Main VI so you can edit it

Now that you have that VI, you can open it up and continue on. Yay!

Inside that VI, there is a "Get On PC" VI inside the "1, 2" case in the middle case-structure. We had to edit that too :-)

Get on PC:
Since this VI is also a clone, do the same steps as above with the MJPG VI, (but, obviously, look for the Get On PC instead )

Moving on...

All we had to add was a control for the camera port and make it an input for the VI.


That's what we did. Let me know if you have any further questions at all.

Thanks again Greg for getting us on the right foot

[Greg McKaskle]

You are welcome. Glad you got it working and are willing to share the results.

Also, if you have a reentrant clone VI and need to edit it, press ctl-m, which is a shortcut for Operate >> Change to ... Mode. This lets you go between run and edit mode for any VI. Clones default to Run Mode.

Greg McKaskle

[jojoguy10]

Originally Posted by Greg McKaskle

You are welcome. Glad you got it working and are willing to share the results.

Also, if you have a reentrant clone VI and need to edit it, press ctl-m, which is a shortcut for Operate >> Change to ... Mode. This lets you go between run and edit mode for any VI. Clones default to Run Mode.

Greg McKaskle

Glad to help out other FRC'ers :-)

And thanks for that tip. That's MUCH easier than what we had to do

[teku14]

Thank you all for the response! Extremely helpful. I will try this out and post how it turns out.

[teku14]

I'm sorry but even after following your instructions and pictures to the dot it doesn't seem to be working. Also the code you attached is trying to access the default WPI VIs that are on my computer. Can you save the modifications you made to the WPI Camera VIs into the project as new VIs and repost it?

[bvisness]

Glad you guys got it all working! Just a piece of advice from a former driver, though – you will probably not be looking at your driver station laptop nearly as much as you think you will. Driving is stressful and dangerous and it's hard to tear your eyes away from the field and down to your computer.

That's my experience anyway. Just something to keep in mind!

[jojoguy10]

Originally Posted by bvisness

Glad you guys got it all working! Just a piece of advice from a former driver, though – you will probably not be looking at your driver station laptop nearly as much as you think you will. Driving is stressful and dangerous and it's hard to tear your eyes away from the field and down to your computer.

That's my experience anyway. Just something to keep in mind!

Thanks for the advice! I was the driver for our team for 2 years, and I can concur, however , with how little visibility there is on the field this year, it will be difficult to see what's in front of your robot at times (e.g. a boulder behind the drawbridge).

We have tested the latency on the camera over wifi from the robot (not through the FMS, so it might vary), and it isn't that bad. We calculated it to be only about 90-100ms lag. We had our driver drive it a bit ONLY looking at the webcam image, and he said he could drive it just fine.

[jojoguy10]

Originally Posted by teku14

I'm sorry but even after following your instructions and pictures to the dot it doesn't seem to be working. Also the code you attached is trying to access the default WPI VIs that are on my computer. Can you save the modifications you made to the WPI Camera VIs into the project as new VIs and repost it?

I will post the VIs. I will try to get them out before the end of the week (school, work, robotics, etc )

Also, I double-checked the rules, and we're not allowed to use port 1181. We have to use a port somewhere in between 5800 and 5810 (per R60)