Am considering using an Arduino Mega for a UAV project. We will most likely be interfacing with DIYDrone's APM2 autopilot board. The real complexity comes in where we are hoping to interface with a DSLR camera, take pictures off the SD card, or via USB realtime, and transfer the data to a ground station at at least 1-2 mbps using an ubiquity bullet device (rated much higher than this data transfer rate up to several miles). We are trying to decide if we need to go ahead and getting an embedded single board microcomputer i.e. with atom processor and all, or stick with the arduino. I've done a fair deal of Arduino projects, but nothing to this extent.
Are you planning to transmit the entire image from the DSLR in real time? I suspect the arduino just will not be able to handle that amount of data. Even if the arduino is fast enough, is your comm link fast enough to get the whole data flow fast enough to be able to be useful? My E-5 currently generates 4-7 megabytes per picture for JPG images, and RAW images are larger.
Depending on the DSLR, you have the problem of getting the image from the camera to the arduino for transmission.
I suspect instead of sending the whole image, what you want to do is run the DSLR in live view mode and use the video out feature of the camera to get a composite video stream out and still record the hi-def images on the camera's memory card. Then you would presumably use the normal means of sending video through your comm link (I assume sending composite video is already handled).
If it wasn't an airplane, you could use either Eyefi cards to transmit the images directly over wifi or the various wifi based solutions intended for car backup monitors, but I suspect the plane would be outside of the range of a normal wifi setup.
ubiquity offers essentially a wifi module called the bullet that is essentially just a standard wireless network for long ranges and high data transfer rates. Picture clarity and resolution are very important because the images will be analyzed using openCV to find various glyphs on the ground. This is the reason why we decided not to go with video and pictures instead. Assuming we went through USB, are you saying the arduino serial communications would bottleneck the process? There are publically available serial protocols for DSLRs I believe, but I imagine either the arduino or the ethernet shield (which the bullet plugs into), would slow things down majorly.
The flow I should have put in the post, which I don't even know if it is compatible:
Camera>USB>Arduino serial port>ethernet shield>bullet wifi device>ground antenna>ground computer
jgeating:
ubiquity offers essentially a wifi module called the bullet that is essentially just a standard wireless network for long ranges and high data transfer rates. Picture clarity and resolution are very important because the images will be analyzed using openCV to find various glyphs on the ground. This is the reason why we decided not to go with video and pictures instead. Assuming we went through USB, are you saying the arduino serial communications would bottleneck the process? There are publically available serial protocols for DSLRs I believe, but I imagine either the arduino or the ethernet shield (which the bullet plugs into), would slow things down majorly.
The flow I should have put in the post, which I don't even know if it is compatible:
Camera>USB>Arduino serial port>ethernet shield>bullet wifi device>ground antenna>ground computer
It depends on the DSLR. My Olympus cameras don't have a public protocol for uploading. I haven't done the math, but from what I've read in other posts, the Arduino is just to slow to keep up with the data stream. I know it can't keep up with video unless you reduce the picture size to something like 160x120 black and white images.
If the bullet is just standard wireless, and your DSLR takes SD cards, I would look into Eyefi cards. These are used like memory cards, but can communicate via wifi networks to upload the photos as you take them. Unfortunately, they don't support CF cards, and using a CF->SD card adapter either doesn't work, or it reduces the wifi range drastically. I would imagine the heavier DSLRs may provide shielding, and you may need to get the wifi receiver antenna close to the camera.
However, the above is guesswork, and such. You won't know until you actually try it.