"Dhrishya"- Software for real time display of images captured onboard at mission control center
- Paper ID
92452
- author
- company
Vikram Sarabhai Space Centre, ISRO, Thiruvananthapuram
- country
India
- year
2025
- abstract
Dhrishya is a software designed for real time display of images captured by onboard cameras and associated electronics and transmitted through telemetry during a satellite launch vehicle mission. This is a software of significance developed at VSSC, ISRO. The task of capturing events during the ascent flight of a satellite launch vehicle is undertaken through Onboard Imaging system. This is a reconfigurable wavelet based system and utilizes the latest still image compression standard – JPEG2000. It acquires images from cameras mounted at suitable locations on the launch vehicle, compresses it and transmit to various ground stations including Trivandrum, Sriharikotta, Portblair, Mauritius, Brunei and Baik. The Dhrishya software accepts the compressed image data, decompresses it and displays the images in real time during the launch. It plays a pivotal role in the visual confirmation of major events like stage separation, engine ignition, space surveillance etc and it can also be used as a vital tool for failure analysis, if needed. The development of Dhrishya software was a technically challenging task as all the images of various events need to be displayed without any error and in near real time. Optimized implementation of various modules in the algorithm was the most challenging task so that the software runs fast enough to enable decompression and display of one set of image data before the next image data set is received. With an allocated bit rate of 500Kbps and a compression ratio of 30:1, the image will be arriving at an interval of 0.3sec.Accordingly, execution time for decompression and display of an image should be less than 0.2 sec. During the course of flight of launch vehicle or interplanetary probes, all measurements are send through a wireless telemetry link to earth. The image data which is embedded in the total telemetry data received at ground stations are send through optical cable using UDP to real time mission consoles at Sriharikota. The Dhrishya software accepts the stripped compressed image data. Using the header information embedded in the compressed data stream, the software separates data into different image files. The decompression module of the software accepts the data in real time,decompresses the images and displays on monitor. This software is currently used for all ISRO missions, for displaying images in live mode on all television channels. Real time display system based on advanced image processing algorithms is a mandatory significant system for all future ISRO missions.