Cartosat-1 10 years and beyond

Transcription

1 nrsc Cartosat-1 10 years and beyond Cartosat-1 : 10 years completion in Orbit ( ) 5th May 2015 National Remote Sensing Centre Indian Space Research Organisation Dept. of Space, Govt. of India Balanagar, Hyderabad bhuvan.nrsc.gov.in National Remote Sensing Centre Indian Space Research Organisation Dept. of Space, Govt. of India

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3 Cartosat-1 10 years and beyond Cartosat-1 : 10 years completion in Orbit ( ) 5 th May 2015 Part of Chandigarh National Remote Sensing Centre Indian Space Research Organisation Dept. of Space, Govt. of India

4 Editors Dr/Sri/Ms B. Gopala Krishna K. Venugopala Rao E Vijayasekhar Reddy Bhavana Sahay Tapas Ranjan Martha P. Srinivas B. Narender T. Sivanarayana Ch. Venkateswara Rao Cover-1: Front cover - Dubai International Airport, Dubai Cover-2: Part of Antarctica Cover-3: Perspective view generated using CartoDEM shows twin reservoirs of Warasgaon and Panshet near Pune in Maharashtra state.the Welhe reservoir and its dam is seen in the left part of the image. Cover-4: Back cover - Santa Cruz, Bolivia Printed at Map Printing Facility, PPEG, NRSC

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7 : : Dr. V. K. Dadhwal Preface Cartosat-1 has successfully completed 10 years in orbit and has acquired stereoscopic images of national and global coverage. Wide swath and high resolution metric quality stereoscopic images have made significant contribution in the field of satellite photogrammetry as a time and cost effective solution for topographic applications. The higher stability of the spacecraft and high geometric fidelity of imaging have given the advantage of accurate photogrammetric bundle block adjustment of large number of stereo models with optimised GCPs. The sensor independent Cartosat-1 Orthokit datasets with RPC has helped in generating maximum number of user request products. This has led to the development of operational satellite photogrammetry and generation of national level DEMs, DTMs, ortho-images and value added PAN sharpened products. Today Cartosat-1 based datasets have become standard products for Bhuvan in high resolution image reference and development of many national level natural resources development applications and management programmes in different themes such as agriculture, urban planning, water resources, irrigation potential development, landslide studies, glacier studies, ground water potential zonation, disaster support, rural development, decentralised planning, forest biomass estimation, etc., A comprehensive compendium Cartosat-1: 10 Years Completion ( ) has been brought out on this occasion. This includes various aspects of Cartosat-1 mission its overview, payloads, processing and product generation and data utilization. Also covered are initiatives like Ground Control Point Library and CartoDEM. The use of Carosat-1 along with PAN and LISS-IV sharpened products for generation of large scale thematic mapping has made significant impact in the development of various national level EO application products. This compendium integrates inputs from all ISRO centres who are partners in the Cartosat-1 mission. I take this opportunity to express my sincere thanks to the contributors for their effort. Hyderabad Director Government of India Department of Space National Remote Sensing Centre Balanagar, Hyderabad , Telangana, India Telephone : Fax : NRSC (V.K. Dadhwal) Director, NRSC Indian Space Research Organisation

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9 Contents 1. Indian Remote Sensing Satellite - Cartosat-1 Mission Cartosat-1 Payloads Data Processing, Product Generation, Evaluation & Dissemination IGS Installations CartoDEM-National DEM Generation Project Cartosat-1 Data Processing and Applications at ADRIN Cartosat-1 Data Utilisation and Applications 119 Cartosat-1 Data utilisation Outcome / Achievements - RSAA, NRSC Totographic Mapping - AS&DM, NRSC Space based Information Support for Decentrilised Planning (SIS-DP ) - Regional Centers _NRSC Studies carried out at Space Applications Centre, ISRO, Ahmedabad 8. High Resolution Satellites of India beyond Cartosat Major Accomplishments of Cartosat-1 during the 10 years of its 189 mission life A Summary Cartodat-1 Related Publications NRSC

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11 SC N R Cartosat-1 Data Processing and Applications at ADRIN Chapter 6

12 Cartosat-1 Data Processing and Applications at ADRIN Introduction Data Procurement and Production at ADRIN Data centre Data Processing & Product Generation methodologies Evaluation of the Mapping potential of Cartosat-1 Control extension Value Added Product Generation System Bundle Block Adjustment Package (BBA) Island Information System Summary of Achievements Contributed by ADRIN Team NRSC

13 Introduction The entry of Cartosat series in Indian Remote Sensing (IRS) satellites opened a new chapter in the exploitation of High Resolution Satellite imagery (HRS) for 3D mapping. Large swath, highresolution and stable imaging configurations are the key features of Cartosat-1, which make it suitable for large scale mappingover large areas. ADRIN has attempted for the full exploitation of the potential of this data. The classical satellite image processing methods were modified in order to describe the imaging geometry. In general, the processing of these images provided a challenge for algorithmic redesign and this opened the possibility to reconsider and improve many processing components such as image enhancement, image orientation (georeferencing), orthophoto & DEM generation, object extraction and 3D visualization. Large number of data sets is being procured by ADRIN for users. Also, many application packages are developed for Value added data products generation and for catering to the needs of the user community from Cartosat-1 data. Fig.1 shows these three components towards the effective utilization of Cartosat-1 data. Fig.1 Three components towards the effective utilization of Cartosat-1 data Data Procurement and Production at ADRIN Data centre NRSC For user community, ADRIN is responsible to procure data, convert into a correction level and format in which they want and get delivered. Few users wanted ortho and DEM products whereas others wanted long strip data and corresponding RPCs for processing rather than subscenes, so that they can do control extension. For this purpose, RPCs were regenerated corresponding to image data of 500km length using ADIF, concatenated sub scene data from orthokit and delivered to the user. Also, thousands of products were generated at ADRIN Data Centre towards various user projects. Total number of Cartosat-1 datasets procured and processed towards various projects at ADRIN is about ADRIN Data Centre generated 19,000 Cartosat-1 products of 1:25,000 map equivalent areas. Data Processing & Product Generation methodologies Many new ideas were developed and tested for processing and product generation from Cartosat-1 data. Following are few of them. 111

14 Full pass /long strip adjustment Along-track stereo processing Tied camera approach for sensor model - In the tied camera approach for sensor model, fore and aft images are treated together. That means modeling of 52 seconds of imaging geometry and process at a stretch. The unknown parameters of both images are computed together. The most important requirement is to understand the satellite motion and to represent this motion using a set of equations for position and orientation. The challenge of developing a combined camera model for Cartosat-1 is to find common parameters for both images and to establish their relative orientation. The benefit is that the number of unknown parameters is reduced. Iterative Ortho image Refinement (IOR) method for DEM generation - IOR method utilizes the capability of Cartosat-1 and availability of public domain DEM like SRTM data to generate and simultaneously edit good quality DEM. The main advantage of this process is to utilize the inherent geometric relationship between the Digital elevation model and ortho image to automatically edit the generated DEM. DEM generated through IOR is superior to the DEM generated through direct intersection method in bringing out minute details of the terrain. Data Product generation packages like VAPS and BBA which are operational at user end uses this approach for DEM generation. Bundle Block Adjustment - In this approach, images from multiple dates/sensors are adjusted together by exploiting the individual viewing geometries and camera geometries. Interior and exterior orientations of the cameras are done with the same model.the block adjustment model is directly related to the geometric properties of the physical sensor model, by combining multiple rigorous sensor model parameters into a single adjustment parameter having the same net effect on the object-image relationship. Consequently, the block adjustment method is numerically more stable than the traditional adjustment of exterior and interior orientation parameters. Weak convergence criteria are also included while processing the tie points. Extending the basic principles of block adjustment into satellite imaging geometries was a big challenge. In-flight geometric calibration - The objective of in-flight calibration is to ensure the best location performance of both cameras and to ensure same relative location accuracy between them. As part of it, individual sensor alignment calibration, inter-camera alignment calibration and focal plane calibration are done. Taking advantage of the same orbit acquisition, calibration of different cameras is done with rigorous geometric reconstruction of the sensor orientations. At ADRIN, we have done in-flight calibration periodically and modified the alignment offsets in the processing software. Different orbit Attitude correction methods RPC generation and processing Intersection of multi-resolution images for DEM generation (with SPOT and Cartosat-1) Pan Sharpening of Cartosat-1 with multispectral (RS1/RS2 L4) for better spatial and spectral resolution. Wide mono image from Cartosat-1 is having a swath of around 60km and is ideal for PAN sharpening with RS-2 LISS-4 full MX product. Fig.2 shows a sample product of Cartosat-1 Wide Mono merging with RS2 L4FX. NRSC 112

15 Fig.2 Cartosat-1 Wide Mono merging with RS2 L4FX in FCC & NCC Fusion of overlapping DEMs, generated from Cartosat-1 data captured from different acquisition techniques, dates or from different times to find inconsistencies, improve density, accuracy and eliminate gap. Fig.3 gives an example. NRSC Fig.3 DEM fusion Evaluation of the Mapping potential of Cartosat-1 Cartosat-1 is a very stable satellite meant for mapping applications. ADRIN has conducted a pilot study to evaluate the mapping potential of Cartosat-1 satellite. To check the achievable accuracies, we have used the base maps, which are of 70cm accurate, as reference data. Accuracy evaluation is done over 6 data sets. Only a single GCP is used for orientation of the 113

16 sensor in all the cases. Area covered in each data is 30kmX30km. Distributed Check points are identified. Errors obtained for different datasets are shown in Fig.4. GCP requirement is minimized by using the ephemeris and attitude data and precise payload geometry in to the rigorous sensor model. Appropriate weight matrices are also used in the adjustment. Fig.4 Accuracies from Cartosat-1 using Single GCP It is clear from Fig.4 that Cartosat-1 data is capable of giving 3-4m accuracy just with one GCP. DEM and ortho were generated using a rigorous sensor model and IOR algorithm. Fig.5 shows the contours generated from the DEM over an area where height range is about m. The kinks in the contours are exactly falling over the ridges. Fig.5 Contours generated from the Cartosat-1 DEM Vector layer from the reference data is overlaid on to the ortho image generated from Cartosat-1 as shown below in Fig.6. All road networks and other features are exactly sitting over the image. NRSC Fig.6 Reference Vector Layer overlaid on to Cartosat-1 Ortho Image 114

17 It is concluded from this pilot study that Cartosat-1 DEM, geometric accuracy and capability for topographic feature capture are good enough for making 1:10000 scale maps. Control extension To check the possibility of using Cartosat-1 data for control extension, a ground truth verification exercise was done along with Survey of India. For this, three strips each of 500km were identified within the country (Rishikesh, Delhi and Hyderabad). World View data over a small pocket in the beginning of the strip was provided for the provision of GCPs to Cartosat-1 Strips. ADRIN generated three ortho products each of 500km length using in house developed product generation package and provided to Survey of India for verification. ADRIN representative also participated for the ground truth trials. The results of the absolute difference between surveyed controls and corresponding points identified on Cartosat-1 are provided in Fig.7. Absolute accuracy of World View which is used as reference is also given in Fig.7. All these areas show an average error of the order 5.16m in latitude direction and 6.79m in longitude direction with respect to surveyed controls. Even though the controls used are in Rishikesh area, products generated over Mathura, which is 300km away show the same accuracy. The results demonstrated the geometric fidelity and capability of Cartosat-1 imagery for control extension. NRSC Value Added Product Generation System Fig.7 Result of Ground Truth verification First version of DEM and ortho generation software using Cartosat-1 stereo pair was developed at ADRIN and made operational at different user sites since 10 years. This is with adjustment of single stereo pair at a time. This s/w is being operationally used for Value Added Product Generation in the IMGEOS chain at NRSC. 115

18 Bundle Block Adjustment Package (BBA) In the context of increasing availability of high resolution data from different sensors and heterogeneity of the data sources in structure, and geometry, a method for geometric data integration and harmonization is required for mapping of multi-resolution data. With this aim, BBA was developed. The system will effectively handle the end-to-end chain in large area mapping and production with good level of automation and the provisions for intuitive analysis of final results in 3D and 2D environment. The package has undergone a rigorous T&E and is installed over three user agencies. It is planned to generate DEM and ortho images over 8 neighboring countries using this software. A large area canvas generation done at ADRIN (Fig.8) using Cartosat-1 images with seamless continuity demonstrates the capability of the s/w. Island Information System Fig.8 An overview of products generated from BBA using Cartosat-1 NRSC Ortho images and DEMs (over selected areas) were generated from Cartosat-1 stereo imagery covering the western coastal belt of India. Resourcesat-2 LISS-4 datasets over the same area also processed for PAN sharpening of Cartosat-1 imagery. Unlike other terrain types where man-made or natural features will be available for matching between reference image and target image as well as between the images in the stereo pair, island mapping posed different type of challenges for automatic DEM and ortho image generation. Main difficulty was due to failure in automatic GCP/Tie point identification because of very less land portion, water body shrinkage /variation in target image compared to reference image, loud cover over many portions, different reflections in Cartosat-1 stereo pair, band to band registration issues in LISS- 4 due to moving wave pattern etc. These issues led to the development of different data error minimization strategies and DEM post processing tools. These ortho images serve as the base layer for Island Information System (IIS). Using the orthorectified images, different layers are created including vector shape files, annotations and statistics and are included in a GIS database of the selected region for a multi-disciplinary study relating to Emergency and Socioeconomic Planning. Fig.9 shows a sample data from IIS. 116

19 Fig.9 Inactive volcano - to the north east of North Andaman with a diameter of approximately 2 km Almost entire island (including the crater) is covered with dense vegetation. The island is part of a wildlife sanctuary and is uninhabited Summary of Achievements Following are few specific achievements and success stories at ADRIN through the data utilization of Cartosat-1. Design and development of an end-to end system for block adjustment and value added product generation is a major achievement. The system was tested with huge blocks of stereo images from Cartosat-1. Development of bundle block adjustment algorithm was a big break through which changed the product generation scenario drastically. The application package, called Bundle Block Adjustment system (BBA), is installed at 3 user sites and is being used operationally. A plan is worked out to generate DEM and ortho images over eight neighboring countries (~25,000 stereo pairs) using this software. Pan Sharpening of Cartosat-1 with multispectral (RS1/RS2 L4) for better spatial and spectral resolution. Island mapping is a unique experience with Cartosat-1. Production of around 19,000 ortho images (each one equivalent to 1:25,000 map area) at ADRIN Data Centre was an achievement. Development of methodology for fusion of digital elevation models generated from Cartosat-1 over different dates and seasons to improve quality was a new and innovative idea. Iterative ortho refinement method for the simultaneous generation of DEM and ortho was a new idea which is totally different from the conventional methods.ior DEMs were compared with DEMs generated using other methods and proved to be superior in capturing finer details of the terrain. NRSC 117

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21 nrsc Cartosat-1 10 years and beyond Cartosat-1 : 10 years completion in Orbit ( ) 5th May 2015 National Remote Sensing Centre Indian Space Research Organisation Dept. of Space, Govt. of India Balanagar, Hyderabad bhuvan.nrsc.gov.in National Remote Sensing Centre Indian Space Research Organisation Dept. of Space, Govt. of India