Transcript: Geotagging Images in Ground Control Software
Hi, for this video, I’m going to show you how to geo-tag images that have been captured from either your last flight mission or any other flight mission that has been previously completed.
The geo-tagging of images in this tutorial will be carried out with the same ground control software you used to plan your flight mission.
To utilize the geo-tagging portion of your ground station control software, you will need to have flown a mission with one of our RGB color-camera-payloads (The Ricoh PX for the Zephyr 2 or the Sony NEX 5 camera for the Zephyr 3).
Geo-tagging the images captured with our multispectral camera payload, the Tetracam ADC Micro, is now done automatically through the camera’s firmware.
By carrying out the geo-tagging process, all we are doing is associating our GPS time stamps recorded by our ground control software with the time stamps saved within our flight mission image data, or EXIF data, recorded during the same flight mission.
Now, the first thing we will do to start this geo-tagging process is source the log file we produced using our ground control software for the flight mission in reference.
The flight mission log file is always automatically saved for the flight operator on the ground station PC’s hard drive, specifically in the ground station’s software program file.
The ground station flight log file name will include, by default, the time and date so that you can easily verify which flight log should correspond to the flight mission you are trying to analyze.
Once you have sourced the flight mission log file you need, you’re going to want to extract the SD card image information from whatever payload you were flying at the time, and put all of these images into an empty folder on your hard drive for geo-tagging.
Image data is easily exportable from your UAV by ejecting the SD card from the payload you were using after performing your flight mission.
Once you have your log file and image set handy, you’re going to want to hit ctrl+F to bring up the geo-tag flight options menu.
You’ll have a screen pop up here, and from there, you’ll see a button that says ‘geo-reference images.’ Go ahead and click that to get started geo-tagging the images.
Once our geo-tagging menu pops up, we’ll just click ‘browse log’ and select the log file we have pulled from our hard drive earlier that has our date and time stamps on it.
From here, we’re going to hit the browse directory button and choose the file folder that we have previously used to store all of our different images from the flight mission in question.
I have a folder named RGB here that we will select, and once we have selected that, we are ready to pair each set of data and estimate the offset in between the time from when we started the mission to the time that the first picture was taken so that the program knows which GPS waypoints are associated with each image.
To do this, we’re going to click ‘estimate offset’ and the program will read the log file we have given and associate our two sets of data together.
Once we have estimated our offset, which you can see is set to -6247.216, we’ll simply copy and paste that number into the ‘seconds offset,’ box, and once we have done that, we’ll select ‘do it.’
The program will now associate our data pairs together, and you will be able to see a match for each image of our photo set.
So If you have 35 images in your image file, you should have 35 matches if everything pairs up.
After your pairing has been confirmed, go ahead and select ‘Geo-tag images’ to start updating all of your image EXIF metadata data so that each image in your data set has an x, y, and z coordinate associated with it—or the actual latitude, longitude, and altitude at which the picture was taken.
When you import these now geo-tagged images into a post-processing software such as Agrisoft Photscan Pro or Pix4D, the program can identify the exact location and altitude of that image, so that, when photo-processing occurs with the program, the end result offers high-quality data without expending a large amount of system resources and time to perform image data processing.
Even though most post-processing programs can align and process data without needing to first geo-tag the image data, I always recommend geo-tagging your images for the best possible result.
You’re going to go ahead and wait until the program has completed its geo tagging function before moving on, but a message will always alert you when this process has been completed.
You can also generate a KML file from these images when you are done, which will allow you to upload a file directly to google earth so that you can immediately see your image data laid out for you.
Normally, to get a more accurate KML file, you should use post-processing software such as Agrisoft Photoscan Pro or Pix4d, as I mentioned earlier.
Pix4d actually has a menu to geo-tag images by using a Mission Planner log file as the ground station software uses here, however, I prefer to geo-tag the images in the way I have shown you because it tends to be a more consistent way to geo-tag images.
So that’s the process for geo-tagging images, if you have any questions, feel free to contact us through email or by phone and we’d be happy to help!
Thanks for watching and happy flying!