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Q1.What are the pre-requisites for using the NRSC's ‘Image search' facility?
Q2.Where can I find out more information about IRS satellite specifications?
Q3.Whom shall I contact regarding technical support questions?
Q4.How long will it take for me to receive data?
Q5.What are the revisit intervals?
Q6.What type of processing is done at data processing systems?
Q7.What are the formats in which digital data are supplied?
Q8.How to read them in ERDAS and ENVI?
Q9.How can I know about the latest product announcement?
Q10.What is cloud cover threshold?
Q11.Are the data sent through network?
Q12.What are the resampling techniques employed on the data?
Q13.What are the available Earth Ellipsoids options?
Q14.what are the various projections in which data are supplied?
What are the pre-requisites for using the NRSC's ‘Image search' facility?
Users need to have a JavaScript enabled browser in order to use the new browse facility. Users are requested to follow the instructions given below to enable JavaScript in their browsers. Here, there are two possibilities:
- Your browser may not support JavaScript
If your browser does not support JavaScript, you must upgrade to a newer version. We recommend using Internet Explorer 5 or higher or Netscape 6.
- JavaScript may be disabled
If JavaScript is disabled in your browser, you must enable it in order to continue. To enable JavaScript, please follow the instructions given below for your browser.
Internet Explorer 5 or higher:
Click Tools and then click Internet Options.
Click the Custom Level button.
Scroll to the Scripting section.
Check Enable under Active scripting.
Allow paste operations via script, and Scripting of Java applets.
Internet Explorer 4.x :
Click the Settings button.
Scroll to the Scripting section.
Check Scripting of Java applets and Active Scripting.
Netscape 6.x :
- Click Edit and then click Preferences.
- Check Enable JavaScript for Navigator.
Netscape 4.x :
- Click Edit, then click Preferences.
Users need to have java plugin 1.4 & above supported by their browsers.
In order to check the support of java plugin, please follow the instructions given below for your browser.
- Go to Start Menu --> Settings --> ControlPanel.
- Check whether Java Plugin is available.
- Then Right Click & Open
- Click the Browser tab and verify whether I.E & Netscape are selected.
- If not selected, then select both the browsers I.E & Netscape.
- Go to Cache tab make the size unlimited if maximum option is selected.
Where can I find out more information about IRS satellite specifications?
NDC brings out Handbooks, brochures, a quarterly newsletter and pamphlets giving all the relevant details for each of the IRS missions. Printed Handbooks are available for IRS-1C/1D and IRS-P4. IRS-P6 handbook and e-brochure are available at our website. Users may download the same. Overview of all the missions is available at ‘Satellites” link on the NRSC web site's page.
Whom shall I contact regarding technical support questions?
You may please mail your questions to the following mail ids :
sales@nrsa.gov.in
feedback@nrsa.gov.in
How long will it take for me to receive data?
Over the period, NRSC has improved the product supply turn around time to better than five days for archived data with standard processing. The TAT is affected by the processing level required. Special products, which involve further processing, may take a couple of days longer. The TAT is also affected by incomplete information, which calls for more correspondence. Under emergency conditions, data can be provided within 24 hours using network transfers.
What are the revisit intervals?
Each satellite has a specific revisit cycle – the period required to visit the same area, called the nominal revisit period, depending up on the satellite altitude, orbital period and swath. However, by virtue of certain features like roll tilt capability and large swath, some of the sensors have better revisit capability. For example, the Wide Field Sensors on-board IRS-1C/1D/P3 and P6 have a wide swath of the order of 700-800 km with huge side lap between paths. By using a suitable combination of paths we can get more frequent coverage of the same area. The PAN cameras on-board IRS-1C/1D/P6 and Cartosat-1 cameras have a roll tilt capability, which facilitates more frequent coverage. For more information on the revisit cycles of individual satellites please consult the “satellites” link on the home page.
What type of processing is done at data processing systems?
Data are processed to various levels – raw, radiometrically corrected, standard corrected (using system information) and precision corrected. For more information please consult the ‘Products' link in the home page.
What are the formats in which digital data are supplied?
Digital Data are supplied in the following formats
LGSOWG Superstructure Format
Fast Format
GeoTiff-Gray Scale
GeoTiff-RGB
Every digital product, comes with product format document and a meta information file which is a text file containing the details required to open the file like satellite, sensor, number of pixels and lines, Band interleaving, date of pass. This information is adequate for opening the files. For more information on digital formats please contact the handbooks, file format documents.
How to read them in ERDAS and ENVI
Opening a file in ENVI
Go to File , select the option open image file if you know the lines and pixels , other wise select the option “ open external file”, from the pull down menu select “IRS” and then the type of the product . The data will be read from the CD and can be displayed in the DISPLAY window.
Opening a file in ERDAS
In the case of ERDAS, if the data are in TIFF, GeoTIFF or JPEG file format they can be directly down loaded and viewed in the viewer.
If the data are in Super Structure or Fast format, the data need to be downloaded using the following procedure:
After initiating ERDAS, go to the ‘import' option. Click the “ IMPORT” option. A window seeking information regarding the location of the file, destination to be saved at and the type of data will be presented to the user.
For the file type select ‘generic binary'. For the source, select the CD drive and give the file name for the downloaded data in the right hand side box. After doing the selection the user will be presented with a box having queries regarding the data format, columns, rows etc.
In the case of IRS-P6 the CD info file on the CD contains this information, and can be fed directly to the query. In the case of IRS-1C and 1D, the required information is in the LEADER file. After the down loading process is complete, you need to open the viewer and select the file that has been downloaded.
How can I know about the latest product announcement?
NRSC brings out a quarterly newsletter ‘INTERFACE” which is made available at our website as a PDF file and can be downloaded. All the latest information on missions, products and applications of data are published in the newsletter. Product announcements are also published at our website. Announcements are also sent by mail / post.
What is cloud cover threshold?
All data with cloud cover less than ten percent are treated as cloud free.
Are the data sent through network?
Data can be transferred in two modes – ISDN and ftp site. Any user having an ISDN connectivity can approach NDC for the data transfer through net. The ISDN bandwidth at NRSC is 2Mbps. It has a provision of Multi user services with user specific bandwidth. ISDN is a way of establishing high speed connections using regular phone lines.
NRSC also has an ftp site, which enables data transfer through network. All the users who want to avail this facility should be registered with NDC. The registration is done offline. The users need to write to NDC or mail to NDC for registering themselves. While ordering the data, the user needs to specify weather the data have to be transferred through net or not. In case he needs the data through the net, he needs to mention the mode of transfer i.e., ISDN or Internet. Based on the data requirement the data are generated and uploaded onto ftp server. After uploading the user gets a mail with his password. He needs to key the password and download the data.
What are the resampling techniques employed on the data?
Following resampling options are available for geometrically corrected products.
Cubic Convolution (C)
Nearest Neighbour (N)
16 Point Sinc (S)
Kaiser-16 (K)
What are the available Earth Ellipsoids options?
Data Products can be supplied in the following ellipsoids for geometrically corrected products.
Clarke 1866 (C6)
International 1909 (I9)
GRS 1980 (GR)
Everest (EV)
WGS – 84 (W4)
Bessel (BL)
Krassovsky (KW)
what are the various projections in which data are supplied?
User can define any of the following map projections for the standard and precision corrected products
Polyconic (P)
Lambert Conformal Conical (L)
Universal Transverse Mercator (U)
Space Oblique Mercator (S) |
