Wednesday, October 12, 2011

Bhuvan Continues To Be A Mixed Bag As A Citizen Mapping Tool

After my last post on the use of Google Earth to identify illegal mining in Goa, I was curious to find out if I could replicate the same in Bhuvan, India's public mapping portal.

I was disappointed:

1)  There is no historical imagery available, or at least none that I could find.  So I could not pull out older imagery to verify claims made about the presence /absence of mining before a certain date.  This is not due to a lack of older imagery. The Indian Space Research Organization has had a remote sensing satellite program since the late 1980's and imagery  of at least 23 m resolution is available for  the last couple of decades and imagery of 5.8 meter resolution is available for the last 12 years or so (IRS - 1D). The 5.8 m resolution images are fine grained enough to identify large features like open pit mines.

2) I could not find the open pit mines using "search by name". In Google Earth I could zoom onto the area of the open pit mines by searching for the nearest settlement "Maina" which was mentioned in the article on the Goa mining scam by the newspaper Herald.   In Bhuvan, the search by name database works best for towns and cities. The village level data is still incomplete. Even when a small village is present in the database the imagery does not always zoom to that area, nor is the village annotated to allow easy navigation to it. These are the basics of interactive map navigation design and Bhuvan is falling short.

On a general note, its been close to three months since the government announced that 1 meter resolution data will now be available without need for security clearances. Yet Bhuvan still is not streaming imagery finer than 5.8 meter resolution.

On the data download front, elevation data of CartoDEM 1 arc second (Digital Elevation Model derived from Cartosat 1 imagery- 1 arc second corresponds to roughly 30 meters) and Resourcesat-1: AWiFS imagery (56m) of the Indian region can be downloaded from the NRSC Open EO Data Archive. You can choose the product and the area of interest from the Bhuvan interface. The DEM download is a welcome addition. You could previously download 1 km resolution DEM of India from the USGS and also 30 m relative DEM generated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) from NASA.

However, regarding imagery the government's all too cautious approach is perplexing. If 5.8 meter resolution and 1 meter resolution data are available and now cleared for access to all users without further security checks, why not let users download that data too?

1 comment:

  1. Yes that is question which needs to be addressed, and stilll situation is same :)