OpenCV 4.0 - Hackdot

Re:OpenCV 4.0 by ChuckMcM on Tuesday November 20, 2018 @05:38PM (#18498503)

It isn't a question of power, I use a lot of Cortex M machines (32 bit ARM) which can compile C++11 just fine, it is that there is a lot of infrastructure (like you really have to have a working heap system, startup files that know how to build the necessary infrastructure, Etc.) that is intimidating to embedded programmers. Not to mention screwing up the symbol names :-).

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Re:OpenCV 4.0 by Iv on Tuesday November 20, 2018 @08:47PM (#18499588)

I used to like the simplicity of the C API and knowing where buffers were allocated and discarded. Then at one point I took the dive and learnt the C++ API and its memory management scheme. I did not look back. Having all these things automated while still being reasonably predictable is really comfortable!

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Re:OpenCV 4.0 by coder543 on Tuesday November 20, 2018 @05:42PM (#18498533)

mbed makes it pretty easy to get going with C++ on Cortex-M, last time I tried it, but that was over a year ago.

Still, I'm skeptical about how much CV you could actually do on a Cortex-M processor. A few dozen to a few hundred kilobytes of RAM is really limiting when we're talking about just loading up an image from a camera, let alone doing computer vision on that image, unless you pay for a Cortex-M7 to get 1MB of RAM or something really expensive like that... at which point, an entire Raspberry Pi 0 SBC with 512MB of RAM is actually cheaper than just your microcontroller alone.

Of course, the microcontroller boots up instantly and supports incredibly useful sleep modes and a variety of other peripherals... but for raw performance per dollar, the M7s are just so costly.

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Re:OpenCV 4.0 by ChuckMcM on Tuesday November 20, 2018 @05:49PM (#18498590)

> Still, I'm skeptical about how much CV you could actually do on a Cortex-M processor.

You have seen OpenMV right? (https://openmv.io) I've got one of their early cameras (waiting on my H7's).

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Re:OpenCV 4.0 by coder543 on Tuesday November 20, 2018 @05:57PM (#18498634)

Ah, a Cortex-M7 with 1MB of RAM... just like I mentioned. haha, the earlier editions used an M4 with 256KB of RAM it looks like, but yeah.

Do you think you could run the license plate reader you wrote earlier on one of these? What are the advantages you see for this over a Raspberry Pi 0 with a Raspberry Camera module? Or the new, powerful Raspberry Pi 3A+ with a camera module? This is certainly more expensive than either Pi option, with a lower resolution camera.

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Re:OpenCV 4.0 by ChuckMcM on Tuesday November 20, 2018 @06:42PM (#18498938)

I'm reasonably certain it can be run on the H7 but not sure about the H4. It is one of my test cases :-). Note that these chips also include a DDR memory controller so you can put 16MB of RAM on them pretty simply, some of ST Micro's 'Discovery' cards come with this populated, but that is not used on the H4 or H7 camera.

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