As you already know, drone surveying greatly accelerates and simplifies collection of land surface data to create large-scale maps or panoramic images of surveyed objects or landscapes. These maps and large images are stitched together from hundreds or even thousands of high-resolution photos of an area. One thing to remember when planning a drone survey is that to get high-quality results and facilitate image stitching, an overlap between individual images is absolutely essential. Taking images that don’t have enough overlap will lead to inaccurate results or a processing failure when stitching imagery, which will ultimately require repeating the survey to capture the images again.
This week, you’ll be working with 28 individual photographs of a stretch of the Murramarang South Coast Walk captured by a drone. The photographs come in two formats, neatly ordered or jumbled, so you can choose your own adventure. If you decide to work with the ordered photographs, you can proceed straight to stitching them together into a panoramic image. If you want a bit of a challenge, go with the jumbled images and arrange them into a correct sequence before proceeding to post-processing. To figure out how to order the images, you need to pay close attention to the overlap between them. If you see that two photos have the same reference points (e.g., a particular rock formation), it’s most likely that they should be next to each other. If you choose to work with the ordered photographs, take a moment to look at them one after the other and pay attention to how much overlap neighboring images have. One thing to keep in mind is that all images were taken at the same altitude, so they should form a straight line when you order them.
Let’s now dive into your task!
Imagery post-processing check-point
- Access your image dataset
- Select an option of either ordered or jumbled images.
- If you have selected jumbled images, have a go at ordering them. Look for image overlaps to guide you. If you have selected ordered images, take a moment to look at them one after another and notice their overlap.
- Go to GigaPan stitch software website
- Download free 14-day trial version of the software for Mac or PC
- Unpack the downloaded ZIP archive and install the software
- Run GigaPan Stitch on your computer
- When the program starts, press Continue Trial
- Before uploading your images into the program, reduce the number of rows to 1 (as all the images you are using were taken at the same altitude)
- Click Add Images or drag and drop all 28 ordered images into the GigaPan window
- Click Save selection and Stitch
- If a dialogue window pops up, click Turn VC off
- Name your panorama file and click Save
- Wait for the program to do the stitching...
- When your panorama is done stitching,* click on File → Export Stitched Image → select JPEG file format and downsample to ½ size → give your file a name and click Export now
*If you used jumbled images and your final stitched image looks blurry or like its parts don’t fit together, it means that some of the images were ordered incorrectly, so the program had difficulty stitching them together. Have another go at unjumbling the photographs and repeat steps 7-14 for stitching. You can always switch to using the ordered images as well!
- When you are happy with your output, save your final panoramic image to your computer - keep it handy, you'll need it again soon!
You have now had exposure to the key operations that form a drone surveying project! You’ve taken your survey from conceptualisation through prep and planning to data processing and visualisation - well done!