5:15 PM - 7:15 PM
[PPS03-P07] Controlled Color Photomosaic map of Asteroid Ryugu
Keywords:Ryugu, Asteroid
Hayabusa2 ONC (Optical Navigation Camera) has obtained numerous images of asteroid Ryugu. We aim (1) to improve the image geometry information (camera pointing and spacecraft position) and (2) to created high-precision controlled color photomosaic maps of Ryugu. The precise estimation of camera pointing and spacecraft position is the fundamental dataset for investigating Ryugu. We also expect that the maps will be useful for scientists who are not familiar with computer vision in science using the Hayabusa2 imagery.
The ONC consists of a telescopic camera (ONC-T), a wide-angle camera (W1) capable of imaging in the same direction as the ONC-T, and a wide-angle camera (W2) capable of imaging the sides of the spacecraft. In total, ONC has obtained about 8,300 images of Ryugu. The image geometry information of about 7,600 images of them were estimated with high-precision by Sayuri Tanaka using SPC (Stereo Photoclinometry) software created by R. Gaskell. As a result, map projections for those 7600 images are available. Then, assuming that the LIDAR observation from Oct. 2 to 15, 2018 were absolutely reliable, the camera pointing, spacecraft position, and absolute scale of Ryugu were determined (Watanabe et al. 2019). On the other hand, the image geometry information of the remaining 700 images, especially high-resolution images, were not determined for several reasons. It is scientifically important to estimate the image geometry information of these 700 images and to produce local high-resolution maps, because they were taken at close approach phases and observed the surface of Ryugu at the highest resolution (MINERVA deployment, MASCOT deployment, and Touch Down 1 and 2 operations).
We performed a photogrammetric bundle adjustment on a group of overlapping images. We created a control point network to connect each group of overlapping images, at least one of which needs to have geographic information by SPC. The bundle adjustment simultaneously refines the image geometry information and control point coordinates (x,y,z, latitude, longitude, and local radius) to minimize mismatches in control points in each image coordinate. We have developed new software to perform this process efficiently. A series of mosaic maps produced as a result of this work will be archived. Also, this work can be applied to the MMX mission, which plans to obtain more images of Phobos and Deimos.
The ONC consists of a telescopic camera (ONC-T), a wide-angle camera (W1) capable of imaging in the same direction as the ONC-T, and a wide-angle camera (W2) capable of imaging the sides of the spacecraft. In total, ONC has obtained about 8,300 images of Ryugu. The image geometry information of about 7,600 images of them were estimated with high-precision by Sayuri Tanaka using SPC (Stereo Photoclinometry) software created by R. Gaskell. As a result, map projections for those 7600 images are available. Then, assuming that the LIDAR observation from Oct. 2 to 15, 2018 were absolutely reliable, the camera pointing, spacecraft position, and absolute scale of Ryugu were determined (Watanabe et al. 2019). On the other hand, the image geometry information of the remaining 700 images, especially high-resolution images, were not determined for several reasons. It is scientifically important to estimate the image geometry information of these 700 images and to produce local high-resolution maps, because they were taken at close approach phases and observed the surface of Ryugu at the highest resolution (MINERVA deployment, MASCOT deployment, and Touch Down 1 and 2 operations).
We performed a photogrammetric bundle adjustment on a group of overlapping images. We created a control point network to connect each group of overlapping images, at least one of which needs to have geographic information by SPC. The bundle adjustment simultaneously refines the image geometry information and control point coordinates (x,y,z, latitude, longitude, and local radius) to minimize mismatches in control points in each image coordinate. We have developed new software to perform this process efficiently. A series of mosaic maps produced as a result of this work will be archived. Also, this work can be applied to the MMX mission, which plans to obtain more images of Phobos and Deimos.