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

3. Guidelines for feature digitization/abstraction

3.1 The general specifications for digitization are given below:

• 
  The data is to be digitized using heads-up digitization.
  
• 
  The features are to be captured such that the polygon features are put in one layer, the line features are in another layer while the points are in a different layer.
  
• 
  The lines are to be digitized as polylines only, coincident lines are to be digitized once and copied to appropriate layer.
  
• 
  Feature specific codes are to be assigned uniquely as given in the format.
  
• 
  The data should be topologically correct for each of the layer.
  

3.2 The accuracy requirement and specifications for each of the type of features is indicated below:

3.2.1 Polygon feature specifications

• 
  The parcel boundary should be digitized in such a manner that the resulting vector line falls in the center of the raster data image element being vectorized.
  
• 
  The parcel boundaries are generally straight, hence should be digitized using 2 nodes/vertices in keeping with the shape of the polygon.
  
• 
  The feature should be digitized in such a manner that there is no overshooting or undershooting of arcs, or duplicate arcs.
  
• 
  The feature should be captured with specked symbol.
  
• 
  The feature should be digitized with minimal number of vertices while, at the same time, maintaining the smoothness or angularly of the lines, as the case may be.
  
• 
  The feature should be a closed polygon without any dangles or sliver.
  
• 
  Each polygon should have a unique PIN as per the coding scheme indicated below.
  
• 
  The tolerance values for arcs, node snapping and vertices should be such that the features snap within the pixels defining that feature and do not snap outside.
  
• 
  All features like parcels, roads, rivers, etc., which form the polygons, are to be digitized and coded as per the coding scheme.
  
• 
  The connectivity of the rivers/roads is to be maintained and should not be disjointed.
  
• 
  The label (parcel no.) should be placed in the center of the feature.
  
• 
  Nodes are to be added wherever symbols are depicted on the parcel boundaries.