High Class Photogrammetry with Aerial Images from a PAS 280 & Trimble Inpho

[This case study was originally published by Phase One on February 1, 2022]

High Class Photogrammetry with Aerial Imagery from a PAS 280 & Trimble Inpho Software

A Phase One Aerial System 280MP (PAS 280), combined with Trimble® Inpho® software, reached new efficiency levels when processing a classic photogrammetry project for an agricultural customer.

Leveling-up project precision and productivity

Combining a high-quality aerial camera system and complementary software for a complete and seamless workflow is mandatory to level up the precision and productivity of photogrammetric projects.

Improved efficiency was evident in a recent European project, exceeding expectations. A Phase One 280MP Aerial System (PAS 280) and Trimble Inpho software achieved deliverables with the highest productivity.

Faster project area data acquisition

The designated project area was flown in summer 2021 with a Turboprop aircraft at 180 kts equipped with the PAS 280 aerial system. In total, 17 lines were flown at 17,000 ft (5,200 m) altitude with a Ground Sampling Distance (GSD) of 15-20 cm over mountainous terrain.

Images were stored and managed by iX Capture software with GNSS/IMU data from the Applanix 310 system. Aplanix Trimble POSPac software processed the post-flight data.

Aerotriangulation by MATCH-AT

The Inpho MATCH-AT created the aerial triangulation of the project within the selected area of interest with 1,419 images. Some of the provided Ground Control Points (GCP) were used in block adjustment to increase the results' accuracy.

Dense tie point distribution was achieved in all possible areas using the MATCH-AT module's strength in obtaining reliable results, even in challenging areas with less connectivity (e.g. water and cloud coverage).

The quality of the tie point extraction connection resulted in less than 1 sec./image processing time with Inpho, which is well above imagery industry standards.

PAS 280 provides precise point distribution

The PAS 280 proved the excellent reliability of its camera for aerial photogrammetry projects. The block adjustment statistics show that no additional grid distortion correction was needed.

The adjustment statistics show:

• Image matching at 0.28 pixel and GNSS positioning accuracy of about 6cm. Root Mean Square (RMS) values of automatic and manual measurements of 2 µm or less.
• RMS values of the 17 GCP's with 6cm in planimetry and 10cm for the height values.

Generating the DSM & DTM using Inpho toolkits

Due to the project’s rural application, the flight was conducted with a 60% overlap and 40% side-lap to rapidly generate a Digital Surface Model (DSM), with sub-pixel accuracy, using the MATCH-T DSM module in Inpho. In city modeling or urban mapping projects, or in areas with high buildings, as well as high-overlapping imagery projects, MATCH-3DX is recommended.

Automatically generated colorized dense point clouds, in sub-pixel accuracy, were filtered to obtain a Digital Terrain Model (DTM) using the DTM toolkit functionality. The standard settings, as default, provided outstanding results, which improved with customized filter settings or interactive modifications.

Orthophoto generation & mosaicking using OrthoMaster and OrthoVista

The OrthoMaster module in Trimble Inpho software offers a high-performance orthorectification tool, which was able to rectify the images in Orthophotos in less than 1 sec./image.

OrthoVista was used to process the final radiometric adjustment, seamline calculation, and mosaicking. Although this Inpho module is well-known for its strong and automatic ratiometry enhancement capabilities, the refinements of this project were no challenge due to the well-aligned radiometry from the PAS280 images.

Increased productivity in less time

The project provides a fitting example of a solution using Phase One cameras and Trimble Inpho software for leveling up the productivity in high-quality aerial imagery projects. The image matching results represent the power of MATCH-AT in tie point extraction with solid connectivity in the whole block.

The high-quality imagery of a PAS280 and the well-balanced radiometry across the entire project increases productivity by reducing the time for any additional refinement to the automatic steps in orthomosaic generation in OrthoVista.

“The combination of high-quality Phase One cameras and Trimble Inpho suite increases the level of quality and efficiency in the production lines of any imagery project, from small to large scales.”

- Dr. Mohsen Miri, Product Manager of Inpho and Photogrammetry Solutions, Trimble