Draft operational guidelines of digital india land records modernization programme (dilrmp) introduction

Four corner tics available – The tentative distance of the corner tics has to be measured, based on the scale, and highlighted with a cross (X) depicting the tics position.

No gridlines or tics available – This map will have no reference points, but to remove the scanning error, if any, the situation may be rectified by using the transferred tics. The tics from standard mathematical grid (grid will change depending upon the scale) have to be transferred on the analog sheets by overlay method on light-table. These transferred tics will rectify any distortion during scanning of the sheet. However, the map sheet can be corrected by registering the graphical scale with the standard template scale.


2.4 Scanning of the analog maps (converting analog to raster cadastral images)

2.4.1 The cadastral maps are scanned using AO size raster scanner. While scanning, the important parameter -- DPI (dots per inch) -- has to be precisely set. The DPI is based on drawing characteristics and information required. In general, the following minimum specifications should be adopted while scanning the cadastral sheets: Maps should be scanned at 100-200 DPI Black/White (8 bit gray tone) mode depending upon the density of the features. If all the details are not picked up during scanning, the scanning parameters should be changed to 400 DPI on 24-bit color. While scanning, the sheet has to be fed in straight upright position and smoothened so that any fold is not generated while scanning. In the flat-bed scanner, the map has to be laid flat on the glass, smoothened and scanned; and bulging should be avoided.

2.4.2 After successful scanning, the DQC-2 procedure has to be followed. The raster image of scanned map should be stored in TIFF format (*.tif or tagged image format). The scanned map orientation should be upright (north oriented). The scanned map should be cleaned and free from noise (i.e., unnecessary pixels or darkness in the image). To remove the noise, de-speckling should be applied. The measured length and width within the bounding box of the scanned map should be +/-0.1% of the map manuscript measurements. The scanned image should not be skewed or warped; if there are any, it should be de-skewed or necessary correction should be applied, or it should be re-scanned. The scanned image should not have any line dropouts or stretched pixels; otherwise, it will have to be re-scanned. The scanned file will take the name of map index name, such as I120501007035101.tif