APPENDIX

Procedure for Digitization and Updation of Core Network.

A. Map Digitization

1. Feature Extraction

The main source of the spatial data is Survey of India (SoI) maps at 1: 50,000 scale. The boundary of block, division, and circle can be taken from departmental map.

The Spatial database includes following layers

No. / File/Layer name / Map layers / Type
1 / Habitation / Habitations / Point
2 / Bound_State / State Boundary / Polygon
3 / Bound_District / District Boundary / Polygon
4 / Bound_Block / Block Boundary / Polygon
5 / Bound_MPConst / MP Constituency Boundary / Polygon
6 / Bound_MLAConst / MLA Constituency Boundary / Polygon
7 / PWD_Division / PWD Division Boundary / Polygon
8 / PWD_Circle / PWD Circle Boundary / Polygon
9 / Bound_Forest / Forest Boundary map / Polygon
10 / Bound_InterNational / International Boundary (Line) / Line
11 / Road_DRRP / DRRP Road / Line
12 / Road_CN / CN Road / Line
13 / Road_Surface / DRRP Road Surface Type / Line
14 / Road_CN_Segment / CN Road Segment / Line
15 / Bridge / Bridges / Point
16 / LevelCrossing / Level crossing (Manned & Unmanned) / Point
17 / Quarry / Quarry (Stone & Sand) / Point
18 / Market / Market Centre / Point
19 / HQ_Administrative / Administrative HQ (Revenue,Block,District,Panchayat) / Point
20 / WaterBody / Water body / Polygon
21 / Tourist / Tourist Place / Point
22 / Religious / Religious place / Point
23 / Drainage / Drainage / Line
24 / Railway / Railway Line / Line
25 / Drainage / Drainage Catchment / Polygon

2. Tracing

Before start of the digitization the features have to be extracted form the toposheets and traced on the tracing sheet because direct digitization form GT sheet is illegal. The relevant information from various sources needs to be incorporated at this stage.

2.1. Procedure

  • Procure 1:50,000 scale Survey of India (SoI) toposheet of the entire district/state
  • Tracing should be carried out toposheet wise not block wise etc.
  • All features should be traced on the Polyester tracing sheet film using Rotring pens the thickness of tracing film should be 75 micron
  • Unfold a 1:50000 scale Survey of India (SoI) toposheet on the flat table
  • Cut a 75 micron thick polyester tracing sheet of equal size with the shining smooth side directly in touch with the toposheet and the rough side facing up
  • Fix the tracing paper on the map using cello tape etc so it does not move during tracing process
  • Trace the inner boundary of toposheet with 0.5 mm black Rotring Pen
  • Write the reference number of the toposheet on the right corner of the tracing sheet
  • Draw an index map on the bottom right side showing the district/block in the toposheet
  • Mark the the intersection of the various grids on the inner boundary as a small perpendicular line using 0.5 Rottring pen
  • Write the longitude and latitude at the four corners of the toposheet
  • These maps should be thoroughly checked
  • All writing to be done in legible capital letter

3. Digitization

The digitization process can be performed in three principal ways i.e. manual, semi automatic and automatic. The manual digitization can be done in two basic ways one is heads-up digitization another is heads-down digitization. First method uses scanned copy of the tracing sheet in JPEG or TIFF format and digitization is being done on the screen of the computer monitor.Therefore it is also known as on screen digitization. While the heads-down digitization is being done on a digitizing table using a magnetic pen known as Puck These days the heads-down digitization became obsolete as it is a strenuous way of digitizing. Semi automatic and automatic methods of digitizing requires post processing but saves lot of time and resources compared to manual method.

The digitization process thus requires the use of appropriate software. For this purpose ArcGIS Editor, ArcView, ERDAS, AutoCAD, R2V etc. are being used commonly.. If the data has to generated for creating in simple digital format then use of Auto CAD is recommended

3.1 Digitization process

  • Scan the tracing sheet containing the extracted features from toposheets using map scanner
  • Use appropriate software and digitization method
  • Digitize the extracted features in to right type of geometry e.g. habitations into point, roads into polyline/mutiline, block boundary into polygon etc.
  • The digitization output has to be checked by another person
  • After digitizing the different tracing sheets the data has to be mosaiced to form a complete map of area i.e. district, state
  • There are different methods for edge matching or combining various part map to form one complete map of the area using the facility in the software.

B. Updating the Core Network

1. Symbolizing the Core network map

2. Check list for Core Network plan

  • No habitation should be left without mapping on any link/through routes.The same can be checked by habitation wise core net report with blank details
  • If a TR/LR is made from multiple roads in OMMS there should be multiple entries with same LR/TR number for each DRRP road numbers
  • LR/TR number should not repeat in a block
  • Avoid loop formation in link routes and through routes made from VR or ODR
  • Through routes or Link Routes should not cross instead they can merge
  • There should not be any link routes joining two through routes
  • If a TR/LR is crossing the block boundary respective entry with corresponding number in that block should be ensured
  • TR/LR number should follow this format T06, L012 etc. no other alphabets should come in the numbers
  • The numbering of the core network should start from North East corner of the map and should proceed in clock wise direction.
  • If a link route is serving two or more habitations and if the higher population habitation is coming towards market centers, give another link number to the remaining portion of link route.
  • Link or through routes should be provided for habitations only not for any tourist/religious places, unless they are declared through a government notification.
  • Check and recheck the CN map, get it approved and then only make entries in OMMS
  • Make sure that correct data entry has been made at OMMS site