THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION
This paper deals with two aspects of photogrammetric processing of thermal images: image quality and 3D reconstruction quality. The first aspect of the paper relates to the influence of day light on Thermal InfraRed (TIR) images captured by an Unmanned Aerial Vehicle (UAV). Environmental factors suc...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-09-01
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| Series: | The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-1/413/2018/isprs-archives-XLII-1-413-2018.pdf |
| _version_ | 1818956733023780864 |
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| author | A. Sledz J. Unger C. Heipke |
| author_facet | A. Sledz J. Unger C. Heipke |
| author_sort | A. Sledz |
| collection | DOAJ |
| description | This paper deals with two aspects of photogrammetric processing of thermal images: image quality and 3D reconstruction quality. The first aspect of the paper relates to the influence of day light on Thermal InfraRed (TIR) images captured by an Unmanned Aerial Vehicle (UAV). Environmental factors such as ambient temperature and lack of sun light affect TIR image quality. We acquire image sequences of the same object during day and night and compare the generated orthophotos according to different metrics like contrast and signal-to-noise ratio (SNR). Our experiments show that performing TIR image acquisition during night time provides a better thermal contrast, regardless of whether we compute contrast over the whole image or over small patches. The second aspect investigated in this work is the potential of using TIR images for photogrammetric tasks such as the automatic generation of Digital Surface Models (DSM) and orthophotos. Due to the low geometrical resolution of a TIR camera and the low image quality in terms of contrast and noise compared to RGB images, the TIR DSM suffers from reconstruction errors and an orthophoto generated using the TIR DSM and TIR images is visibly influenced by those errors. We therefore include measurements of the UAVs positions during image capturing provided by a Global Navigation Satellite System (GNSS) receiver to retrieve position and orientation of TIR and RGB images in the same world coordinate system. To generate an orthophoto from TIR images, they are projected onto the DSM reconstructed from RGB images. This procedure leads to a TIR orthophoto of much higher quality in terms of geometrical correctness. |
| first_indexed | 2024-12-20T10:58:38Z |
| format | Article |
| id | doaj.art-dc72baa54a7f4eb68e811ab0685b5bb4 |
| institution | Directory Open Access Journal |
| issn | 1682-1750 2194-9034 |
| language | English |
| last_indexed | 2024-12-20T10:58:38Z |
| publishDate | 2018-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| spelling | doaj.art-dc72baa54a7f4eb68e811ab0685b5bb42022-12-21T19:43:05ZengCopernicus PublicationsThe International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences1682-17502194-90342018-09-01XLII-141342010.5194/isprs-archives-XLII-1-413-2018THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATIONA. Sledz0J. Unger1C. Heipke2Institute of Photogrammetry and GeoInformation, Leibniz University Hannover, GermanyInstitute of Photogrammetry and GeoInformation, Leibniz University Hannover, GermanyInstitute of Photogrammetry and GeoInformation, Leibniz University Hannover, GermanyThis paper deals with two aspects of photogrammetric processing of thermal images: image quality and 3D reconstruction quality. The first aspect of the paper relates to the influence of day light on Thermal InfraRed (TIR) images captured by an Unmanned Aerial Vehicle (UAV). Environmental factors such as ambient temperature and lack of sun light affect TIR image quality. We acquire image sequences of the same object during day and night and compare the generated orthophotos according to different metrics like contrast and signal-to-noise ratio (SNR). Our experiments show that performing TIR image acquisition during night time provides a better thermal contrast, regardless of whether we compute contrast over the whole image or over small patches. The second aspect investigated in this work is the potential of using TIR images for photogrammetric tasks such as the automatic generation of Digital Surface Models (DSM) and orthophotos. Due to the low geometrical resolution of a TIR camera and the low image quality in terms of contrast and noise compared to RGB images, the TIR DSM suffers from reconstruction errors and an orthophoto generated using the TIR DSM and TIR images is visibly influenced by those errors. We therefore include measurements of the UAVs positions during image capturing provided by a Global Navigation Satellite System (GNSS) receiver to retrieve position and orientation of TIR and RGB images in the same world coordinate system. To generate an orthophoto from TIR images, they are projected onto the DSM reconstructed from RGB images. This procedure leads to a TIR orthophoto of much higher quality in terms of geometrical correctness.https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-1/413/2018/isprs-archives-XLII-1-413-2018.pdf |
| spellingShingle | A. Sledz J. Unger C. Heipke THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| title | THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION |
| title_full | THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION |
| title_fullStr | THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION |
| title_full_unstemmed | THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION |
| title_short | THERMAL IR IMAGING: IMAGE QUALITY AND ORTHOPHOTO GENERATION |
| title_sort | thermal ir imaging image quality and orthophoto generation |
| url | https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-1/413/2018/isprs-archives-XLII-1-413-2018.pdf |
| work_keys_str_mv | AT asledz thermalirimagingimagequalityandorthophotogeneration AT junger thermalirimagingimagequalityandorthophotogeneration AT cheipke thermalirimagingimagequalityandorthophotogeneration |