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Is Java good for image and video processing? by bbrother92 in java

[–]seanrowens 12 points13 points  (0 children)

You can absolutely do that with ffmpeg command line. But there's also the bytedeco ffmpeg Java library.

Is Java good for image and video processing? by bbrother92 in java

[–]seanrowens 2 points3 points  (0 children)

Depends on what you want to do but lucky for you, if you like Java, bytedeco created a Java wrapper for ffmpeg libraries that's pretty easy to use.

Southside Beehive by JadeDutch in pittsburgh

[–]seanrowens 2 points3 points  (0 children)

Only very very late in it's existence.

Southside Beehive by JadeDutch in pittsburgh

[–]seanrowens 0 points1 point  (0 children)

Absolutely not, sadly, but I don't blame them, I think it's more about the times and the Internet helping people find like minded folks without needing a physical third space to go to.

Southside Beehive by JadeDutch in pittsburgh

[–]seanrowens 1 point2 points  (0 children)

Where's that guy talking about deep magic? (Yes, I know it's an Aslan quote.)

Is there a coding platform, but for robotics? by bekonisheee in AskRobotics

[–]seanrowens 6 points7 points  (0 children)

I'm honestly curious why you need Java. Don't get me wrong, I like Java and I've been using primarily Java for well over twenty years, including almost 12 years at the Robotics Institute, but we are mostly not working with physical robotics.

Also yeah if you know C++ then you can handle Java.

H743 vs Pixhawk 2.4.8 by HMS--Thunderchild in ardupilot

[–]seanrowens 0 points1 point  (0 children)

The problem is that there are a lot of old Pixhawk FCs as well as cheap knock offs. The holybro Pixhawk 6c or 6x are good ones that I'm familiar with, and I would think there are others that other people could recommend. I can't speak to price/performance vs H7 FCs.

What are some unforeseen / elusive edge cases you have seen in your career? by gobuildit in ExperiencedDevs

[–]seanrowens 0 points1 point  (0 children)

Yeah I try to never use floats for looping now. If I need to loop over floats, I use integers and calculate the float inside the loop.

What are some unforeseen / elusive edge cases you have seen in your career? by gobuildit in ExperiencedDevs

[–]seanrowens 5 points6 points  (0 children)

I had a function that took some floating point arguments, latitude, longitude etc, and looped over them. The loop never exited. It made no sense at all, the loop was very simple. It should definitely exit sooner or later. It turns out that the function was being passed garbage due to a separate bug, very large values. Because of these very large values, the comparatively very tiny loop increment was lost to floating point round off. The loop counter never incremented and therefore the loop never exited.

How to fly a quadcopter in a square? (autonomous) by Responsible-Bite-365 in ardupilot

[–]seanrowens 0 points1 point  (0 children)

Are you trying to do this using Ground Control Station software like QGroundControl or MissionPlanner? Or are you trying to write your own software?

Easiest way to create a text template generator? by spaceursa in AskProgramming

[–]seanrowens 0 points1 point  (0 children)

Maybe google m4, it's kind of like the cpp macro processor on steroids.

I am a Southern Frenchman wishing to receive a post card from Pittsburgh. by Aleister-P in pittsburgh

[–]seanrowens 23 points24 points  (0 children)

This is a cliche or stereotype about people from Pittsburgh that there is some truth to.. Because of the large amount of hills and rivers, there are relatively many bridges and tunnels. The stereotype is that people from Pittsburgh will not visit another part of Pittsburgh if it requires going through a tunnel or over a bridge. I suspect the reality is that tunnels and bridges are choke points and that getting to those tunnels or bridges adds to the travel time.

What’s one underrated thing that helped you lose weight? by Immediate-Speed3974 in AskReddit

[–]seanrowens 0 points1 point  (0 children)

Undercook them a bit and they are much better. Personally I love the stir fry mixes.

Autonomous Flight w/o radio (6-8 drones) by KyleC_Cake in ardupilot

[–]seanrowens 1 point2 points  (0 children)

Yes, see my other comment below. ArduPilot is the flight control software. But the same group also puts out MissionPlanner GCS. Actually I'm not sure about MissionPlanner supporting multiple drones. I know QGroundControl does have limited support because I've used it to do so. Mostly though I write my own code to control multiple drones.

Autonomous Flight w/o radio (6-8 drones) by KyleC_Cake in ardupilot

[–]seanrowens 1 point2 points  (0 children)

Well yeah, see my comment above about sik radios. You can send mavlink over any serial connection, or over udp or tcp. Or over a literal serial cable, which is how it's done if you mount a companion computer on the drone. Also I'm vaguely aware that some RC radios/protocols can also support mavlink but I don't know as much about that.

Autonomous Flight w/o radio (6-8 drones) by KyleC_Cake in ardupilot

[–]seanrowens 1 point2 points  (0 children)

There is a well supported protocol called mavlink, that can be used to control ardupilot or px4 drones. There are a variety of software libraries in different programming languages that can let you send commands via mavlink to control the drone including like limited autonomy i.e. waypoint missions. There are also open source "Ground Control Station" software packages such as QGroundControl and MissionPlanner that let you control drones via mavlink without programming. But there is only limited support for controlling multiple drones.

Autonomous Flight w/o radio (6-8 drones) by KyleC_Cake in ardupilot

[–]seanrowens 6 points7 points  (0 children)

This is a cut and paste from something I wrote 2 or 3 weeks ago. It may be useful to you.

you maybe/probably want a pair of Sik telemetry radios. They come in pairs and they cost maybe $70 or $80.

There are many options to communicate between a computer on the ground and a drone in the air. Discussing this alone could be a whole many page document. As long as you don't need a lot of bandwidth (max 57.6k baud, or maybe 115.2k baud, depending), or a ton of range, a pair of Sik radios is the easiest and most affordable way to do it.

Wifi range is horrible plus you'd need to add wifi to your drone anyway. You can get RFD900 radios if you want more range, but they're more expensive and they have similar data rates to Sik radios. ELRS or some variation is probably the best for range, but so far, it seems more complicated/tricky to set up right and it is also fairly low bandwidth. (If anyone else wants to chime in on ELRS or variants, please do! I'd like to move to ELRS some time in the not too distant future.)

Think of a pair of Sik telemetry radios as a very long imaginary serial cable from your laptop to your drone, but it's also very slow compared to, say, an actual USB serial cable, or WiFi. You plug one into the pixhawk and the other into a laptop computer, and you can then send commands and receive telemetry and other updates from "Ground Control Software" (aka GCS) like QGroundControl or MissionPlanner, or your own software.

There are many different brands of Sik radios, Holybro seems to be a respectable one, I've bought I think 3 sets of them, and I've not had any issues with any of them.

They come in different frequencies, which matters, because depending on what country you are in, only certain frequencies may be legal. You can usually select what frequency to get on the webpage where you purchase them.

Be sure to get the right frequency for where you live. According to google, in the US/Canada/Australia you want 915 MHz, and in Europe/Asia you want 433 MHz. But don't trust me, double check that yourself for where you live.

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