I trust that you are already familiar with the following, but I want to take the opportunity to mention a handful of leading reasons why Pix4D’s image processing engine may produce uncalibrated images, which include but are not limited to:
- Blurry or severely distorted image content. It is relatively easy to identify when an image is blurry but consider that linear rolling shutter distortion is not visible to the naked eye in a typical drone flight.
- Insufficient image overlap for the application. The recommended minimum amount of image overlap for any Pix4D project is 75% front and 60% side image overlap, but the minimum recommended amount of image overlap increases to as high as 90% for a low-resolution sensor like the DJI XT.
- Inconsistent or dynamic image content. Low-resolution images are especially vulnerable to image content that is not consistent between overlapping images. Examples of dynamic image content include vegetation on a windy day or the direct reflection of the sun on a photovoltaic array.
- Homogeneous image content. Pix4D’s image processing engine, like, practically speaking, all photogrammetric solutions, relies on unique textures in the image content to identify a common feature in overlapping images. Thankfully much of the world provides us with some texture to work with, but there are project areas that yield little to no usable texture because of the nature of the object.
My understanding is that your latest project results yielded no Automatic Tie Points after processing Step 1. If that is the case, I do not recommend that you incorporate Manual Tie Points as your first plan of attack. Manually calibrating images with Manual Tie Points is a painstaking process that is only possible if you already have a set of calibrated images to tie the uncalibrated images to.
Instead, I recommend that you tailor your project’s processing options to achieve a larger set of Automatic Tie Points and ultimately a robust image block of calibrated images. Considering the intricacies of processing low-resolution thermal images please contact us directly so that we can continue discussing your project’s specific needs.
Thank you for your understanding.