DSM AND TRUE ORTHO GENERATION WITH THE ULTRACAM-L -- A CASE STUDY

Dense Matching is used to match a huge number of pixels automatically to generate a surface model from a set of overlapping digital images. Once a DSM has been processed, it then can be used to generate a so called true-ortho image. Such a true-ortho image has significant advantages over a standard ortho image. Typically, two sensors are used to generate such a true-ortho image: a Lidar sensor system to generate the DSM and an aerial camera to generate the aerial image. Currently another approach is under development which is based on aerial images only. The DSM will be generated by a dense match of the aerial images. The advantage is obvious: only one sensor is required and the expected quality of the true-ortho images is higher due to the higher resolution of the underlying DSM. This case study shows the results of such a dense matching, DSM and true-ortho image generation process based on survey flights undertaken with the new UltraCamL. The UltraCamL is the so called "large medium format mapping camera". It utilizes the concept of the large format camera systems for the medium format market. As a result, the same geometric accuracy and radiometric dynamic can be achieved. The case study shows that this also results in comparable matching mapping and photogrammetry capabilities. The study demonstrates the capabilities of a dense matching approach but also highlights restrictions. Based on that an outlook into the future such as computer vision based classification and DTM filtering is given.