Can anyone tell me how many milliseconds are between the shutter actuation and when the write action begins on the Micro SD card?
Wanting info on setting up Inspire 2 for PPK Mapping with external GPS receiver
- Thread starter timmydjr
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It's likely to be 198ms + the buffer speed. Just saying this because I read where someone was using an electronic flash off a P4, and an I2 with a X5S and a X4S camera, and posted the sync speeds from hitting the shutter button on the RC unit (Not GO 4) to fire a flash in conjunction with the camera shutter in the DJI forum (Bookmarked it here: Using studio flash on a drone. ).
Time to write (Buffer speed) to the SD card will vary depending on the card too. I know I have a 64GB Sandisk with a write speed of 95 and 300, and the 300 speed UHS-II card is much faster to dump the images into on the Olympus camera I use. I doubt if DJI cameras run at top speed though.
My WAG would be around 0.215+ seconds for a starter.
Time to write (Buffer speed) to the SD card will vary depending on the card too. I know I have a 64GB Sandisk with a write speed of 95 and 300, and the 300 speed UHS-II card is much faster to dump the images into on the Olympus camera I use. I doubt if DJI cameras run at top speed though.
My WAG would be around 0.215+ seconds for a starter.
This is related to drone mapping. I am not a hardware I2 guru so maybe what I am thinking can't be done. But looking at this very old post SD activity indicator for Wii it is easy to detect when an SD card is being written to. When doing drone mapping many folks want to have an external GPS receiver on the drones (ie Emlid Reach M+) for PPK (Post Processed Kinematic) accuracy. You must be able to trigger the GPS receiver (called a camera event) the millisecond the photo is taken. You will then go back and Post Process the GPS data for very precise accuracy (meaning each point that was marked by the camera event/actuation). Once you post process the GPS data log, you then update the geotag data in the photos. And then the photos are processed in drone mapping software like Pix4D or DroneDeploy. This is being done on the Phantom 4 Pro by reading the blink of the front light which blinks each time the P4P takes a photo.
If the I2 writes the image data within Milliseconds, and not only within milliseconds, but does it consistently, then you could put an extension cable like this [ http://a.co/d/2KfInuN ] . The sensor would then be tied into that cable to detect the "Write activity" for the photo which would then trigger a camera event on the Reach M+. If it is a consistent delay, say 100 milliseconds, then all the camera events could then be adjusted by -100 milliseconds for very a very precise GPS mark of each photo. Each adjusted point is then post processed from the Reach M+ for accuracy and all the photos are updated with new post processed GPS data.
Now the I2 with X4S camera could be a work horse for PPK drone mapping. In my simple mind this should work but maybe someone who knows all the technical aspects of this can shed some light.
If this can be done, it not only would apply to the I2 but any drone writing to an SD card and able to carry a tiny external GPS receiver like the Reach M+.
Looking forward to some feedback.
If the I2 writes the image data within Milliseconds, and not only within milliseconds, but does it consistently, then you could put an extension cable like this [ http://a.co/d/2KfInuN ] . The sensor would then be tied into that cable to detect the "Write activity" for the photo which would then trigger a camera event on the Reach M+. If it is a consistent delay, say 100 milliseconds, then all the camera events could then be adjusted by -100 milliseconds for very a very precise GPS mark of each photo. Each adjusted point is then post processed from the Reach M+ for accuracy and all the photos are updated with new post processed GPS data.
Now the I2 with X4S camera could be a work horse for PPK drone mapping. In my simple mind this should work but maybe someone who knows all the technical aspects of this can shed some light.
If this can be done, it not only would apply to the I2 but any drone writing to an SD card and able to carry a tiny external GPS receiver like the Reach M+.
Looking forward to some feedback.
Casey, if what I am thinking will work, then it would just be the very first signal of the "write process". So as soon as a write signal is detected (voltage increase) the camera event would be triggered. From the very old post, there are multiple options for detecting the voltage difference on the SD card pin which signals the write process. So no data is being read for this, but simply the initial voltage signal.
Contact Cody remington @ BAAM Tech. He has a turnkey ppk solution for you! Tell him Rob sent you
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