Saturday, May 07, 2005
Mapping the earth from a new high
N. Gopal Raj
With Cartosat-1 in orbit and the launch of Cartosat-2 also planned, the sky is the limit for Indian remote sensing.
IN JUNE 1979, a Soviet rocket carried an Indian satellite that weighed about 400 kg into space. Bhaskara-I was India's first effort at building a remote sensing satellite. Its two TV cameras produced images with a resolution of one km. Only fairly large bodies such as forests, the Sunderbans, Chilka lake, and the mouth of the Ganga could be readily identified from the Bhaskara pictures, recalls K. Kasturirangan, former chairman of the Indian Space Research Organisation who had led the teams that designed and built India's early remote sensing satellites.
On Thursday (May 5), Cartosat-1 weighing 1,560 kg travelled to its orbit in space 600 km above the earth onboard India's own Polar Satellite Launch Vehicle. Its twin panchromatic (PAN) cameras take black-and-white pictures with a resolution better than 2.5 metres, which is sufficient to allow individual buildings to be seen and identified. The images from the two cameras can be combined to produce a three-dimensional effect that allows the height of the terrain to be estimated with considerable accuracy.
The Technology Experiment Satellite (TES) that the ISRO launched in October 2001 and which is still operational carries a PAN camera capable of seeing objects less than one metre in size, a capability that is sufficient to recognise individual vehicles. TES was built in a hurry after the Kargil conflict of 1999 and its images, which are said to be of excellent quality, are available only to the armed forces and security services. One important application of the TES imagery has reportedly been to identify routes that Pakistan-based terrorists are likely to be using to clandestinely enter Indian territory.
ISRO is planning to launch Cartosat-2 with a camera whose resolution will be similar to that of TES before the end of the current financial year. The images from Cartosat-2 will be available on commercial terms.
For ISRO, it has not been a question of only providing images with ever-greater resolution. Many of the remote sensing satellites it has launched have cameras that take pictures in different colours (what is termed `multispectral imagery'), which have poorer resolution than PAN images. Different soils, plants, and minerals have characteristic `signatures' in the various colours and so can be accurately identified in the pictures.
A whole host of applications have grown around using multispectral data. In agriculture, for instance, not only can the different crops be identified but their acreage and even stage of growth can also be gauged. It is then possible to estimate what the likely production would be, well before the crop is even harvested. Multispectral images have also been used to look at forest cover, examine changes in land use patterns, find out where to dig tubewells, make environmental impact assessments, and locate the good fishing areas. Both panchromatic and multispectral images from Indian Remote Sensing (IRS) satellites were used to map the extent of the havoc caused by last December's tsunami. PAN and multispectral images can also be merged to provide the best of both worlds.
But there is no question that high-resolution imageries, which permit rapid mapping in greater detail, have become an important driver for remote sensing. The total worldwide sales of satellite image data alone is forecast to be around $ 1 billion this year (2005), according to Beram Gazdar, senior research analyst at Frost & Sullivan, a company that specialises in consultancy and market analysis. Three-quarters of this will come from sales of PAN data and only 15 per cent will be multispectral data sales, he told The Hindu.
When India's IRS-1C was launched in 1995 (the last Indian remote sensing satellite launched abroad), it was king of the hill with its 5.8 metre resolution PAN camera providing the highest resolution satellite images that were commercially available. It lost that position four years later when Space Imaging, a private company in the United States, got Ikonos 2 with one metre resolution into orbit. Today, another U.S. satellite, QuickBird 2 with a best resolution of 60 cm, offers the highest resolution commercially available images. Future satellites, such OrbView 5 from the U.S., will provide even better resolution. About a dozen remote sensing satellites that are either operational or are expected to be launched by various countries in the next few years (including Cartosat-2) will provide images with a resolution of one metre or less.
PAN images with that sort of resolution (one metre or less) already account for about 23 per cent of satellite image data sales globally, says Mr. Gazdar. However, satellite imagery with a resolution of between one and three metres — the segment Cartosat-1 comes in — is responsible for nearly a third of the satellite imagery sales. So with Cartosat-1 and Cartosat-2, ISRO is well positioned to take advantage of the worldwide market for satellite imagery that is growing at about seven per cent a year, he believes.
Within India too there are signs that high-resolution satellite imagery is becoming popular. Of the Rs.35 crore earned during the financial year 2004-2005 by the National Remote Sensing Agency, the ISRO unit in Hyderabad that handles the reception and sale of satellite data, Rs.6 crore came from the sale of high-resolution data, according to a senior official.
High resolution images are useful for producing detailed maps that aid local level planning and decision-making. In Kerala, for instance, in a project funded by ISRO, scientists at the Centre for Earth Science Studies in Thiruvananthapuram have used Ikonos PAN and multispectral data to update village maps, carry out soil mapping and identify areas that could be prone to landslides. "With satellite imagery, the village maps can be quickly updated," points out K.K. Ramachandran of CESS.
Once data from the Cartosat is available, it will greatly reduce the cost of such mapping, believes Dr. Ramachandran. Although the pricing of Cartosat-1 data has not yet been fixed, ISRO says it is confident the data will be available to Indian users a highly competitive rate.
Handicaps and barriers
But the current regime of security restrictions governing high-resolution satellite imageries could become an important handicap. The CESS scientists, for instance, had to establish their own `ground control points' (GCPs) that are needed to correct the orientation of satellite imageries as the GCPs established by the Survey of India have restrictions attached. The ability of Cartosat-1 to provide accurate height information of the terrain could raise further security issues.
"A major domestic barrier to increased commercial use of remote sensing data within the country has been the various formal and informal norms and rules governing the marketing and distribution of high resolution data," says S. Chandrashekar, a former ISRO staffer and now with IIM Bangalore. In the era of the Internet where such data is available from competing suppliers and can be acquired fairly easily, "the only outcome of such a policy is to deny Indian data acquired by an Indian satellite to Indian users," he told The Hindu. A more pro-commercial data distribution policy was vital, he added.
In 1994, Antrix Corporation, ISRO's marketing wing, signed an agreement with the U.S.-based Earth Observation Satellite Company (which later became Space Imaging, operators of the Ikonos satellite) giving them exclusive rights for marketing and distributing IRS satellite data outside the Indian subcontinent. The agreement has been extended till 2010 and is now principally for data from the Resourcesat-1 satellite that ISRO launched in 2003, according to K. R. Sridhara Murthi, executive director of Antrix. Exclusive rights to distribute data from Cartosat-1 and future Indian remote sensing satellites such as Cartosat-2 would depend on agreement being reached with Space Imaging on its performance targets, he told The Hindu.
Space Imaging had established a worldwide network of IRS ground stations and brought the IRS programme to the international marketplace, a spokesperson for the company told The Hindu by email. Users were starting to value and use multispectral imagery from Resourcesat-1 and the introduction of Cartosat-1 would further increase the commercial marketability of the IRS programme, he added.
Data from ISRO's remote sensing satellites meets eight per cent of the global market for satellite imageries, according to Mr. Gazdar. Rupert Haydn, managing director of Euromap that has been distributing IRS data in Europe over the last 10 years, told The Hindu by email that data from the Indian satellites had a market share of about 10 to 15 per cent in Europe.
The satellite data market had become extremely competitive, pointed out Mr. Haydn. The only way to be successful was to have technically good and reliable products at competitive prices based on a reliable and fast service. He did not, however, respond to a question about whether more needed to be done to improve the competitiveness of IRS data.
ISRO needed to build an brand image for IRS data, says Prof. Chandrashekar. That would not be possible by marketing IRS data through a distributor who owns and operates comparable satellites. India's remote sensing programme had been a technological and organisational success, but now a more proactive strategy was needed to promote and nurture the IRS brand, he remarked.
Copyright © 2005, The Hindu.