This article explains in detail how to verify that there is enough overlap between the images.
To verify if there is enough overlap between the images:
1. Open the images to visualize them.
2. Visually check the overlap between the images. The recommended minimum overlap should be:
- 75% frontal and 60% side overlap in general cases.
- 80% frontal and side overlap for agriculture fields and 85% frontal and side overlap for forests and dense vegetation.
- 85% frontal overlap for single-track corridor mapping. Use 60% side overlap if the corridor is acquired using two flight lines.
For more information on the overlap and image acquisition: Step 1. Before Starting a Project > 1. Designing the Image Acquisition Plan > a. Selecting the Image Acquisition Plan Type.
Verification could be done visually by comparing the shared / overlapping area between two adjacent images. As shown in the below images, the shared area (red rectangle) between the two images is approximately greater than 80% for front overlap.
Article feedback (for troubleshooting, post here instead)
Hello, currently I use SQ+ for mapping our agricultural land with 20 cm/px for GSD (around 212 meters above ground). Now I have project to measure very close object (seedling). By calculating GSD need, I have to 'fly by hand' my ebee drone 1.4 meters above ground to reach 0.26 cm/px GSD. Now my question is how big overlap needed for my case? Is it still 80/60 or 70/50? How about length between route, how to calculate that? thanks
The multispectral camera shouldn't be used to capture images(1.4m) from that low altitude. I would suggest you fly at least 40m height to obtain more reliable data. When flying higher, the images suffer less from perspective distortions, and it is easier to detect visual similarities between overlapping images in vegetation areas.
If you are using RGB camera, then I would recommend you to set a higher overlap of 85% front and 80% side overlap. These parameters can be automatically set using the image acquisition software if there are any that will allow you to fly at that low altitude.
Kapil, thanks for your comments and suggestion. Yes I notice picture distortion when capturing msp camera in the very low altitude.