Jica) Survey of Bangladesh (Sob
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No. JAPAN INTERNATIONAL COOPERATION AGENCY (JICA) SURVEY OF BANGLADESH (SOB) Final Report THE STUDY ON URBAN INFORMATION MANAGEMENT FOR GREATER DHAKA CITY IN THE PEOPLE'S REPUBLIC OF BANGLADESH Supporting Report August 2004 Asia Air Survey Co ., Ltd. SD Aero Asahi Corporation JR 04-17 The Study on Urban Information Management for Greater Dhaka City ) CONTENTS 1. Manual for Digital Topographic Mapping 2. The Term of Work for Preparation of GIS Basic Data 3. Geographic Feature Catalogue 4. Data Structure of GIS Basic Data 4. Field Identification Data (Public facility) 6. Field Identification Data (Administrative name) Manual for Digital Topographic Mapping The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping 1 PREPARATION WORK 1.1 Data Structure of Topographic Data File Topographic data file consists of the following four (4) data types. 1. Line data Line data is the continuous data from the starting point to the ending point. 2. Area data Area data is the data to be obtained as an enclosed feature such as building and the continuous data from the starting point to the ending point. However, the coordinates of the starting point and the ending point shall be same. 3. Point data Point data is the data to be obtained by one (1) point such as symbol of building, vegetation and so on. 4. Text data Text data is the data to be shown by character on the topographic map. Furthermore, above-mentioned data consists of following four (4) attribute data. 1. Layer (level) 2. Color 3. Line weight 4. Line style Layer (level) is the material such as transparent films and, in general, several numbers of layers (levels) will be created according to the planimetric features. Digital topographic maps will be created by compiling these layers as one (1) sheet. Following is the image of layer structures. - 1 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping Image of layer structures Level 1 2 3 Road layer + House and building layer Figure 1.1.1 “Image of layer structure” Accordingly, it is necessary to define the type and attribute of data to be obtained prior to the topographic data file creation. In General, the list of type and attribute data defined for digital topographic mapping is called as Map Feature Code (MFC). 1.2 Map Feature Code As already mentioned in Clause 1.1 “Data Structure of Topographic Data File”, it is necessary to prepare Map Feature Code (MFC) prior to actual digital data acquisition to classify the data to be obtained. On MFC, it is necessary to define data type, layer, color, type of line, and width of line at each item to be obtained. The Digital data shall be obtained according to the MFC. - 2 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping MFC used for “The Study on Urban Information Management for Greater Dhaka City in the People’s Republic of Bangladesh” is shown in Appendix-1. 1.2.1 Point to notice of MFC 1) Level There is level which can be defined in Microstation only to 1 - 63 and it can not define all items by the different level. Therefore, the item that the classification is the same must be defined as the same level. Also, it is necessary to lay down the level to do and to use temporarily as it makes level 63 for work and it uses, and so on, too. 2) Color Color number can be used in 0 – 255. Therefore, all items are different color number and it is desirable to define for them. The color of printing map is defined by this color number. 3) Line style It should classify in the line which isn't symbolized is 0, non-print line is 1, symbolized line is 2. 4) Line weight The line width of printing map is fixed by this line weight. In this study, the relation of the line width of printing map and line weight is as follows. Line weight Line width of printing map 0 0.1mm 1 0.2mm 2 0.3mm 3 0.4mm ・ ・ ・ ・ ・ ・ - 3 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping 1.3 Map Symbols Map symbol is the defined figure to show the object on topographic map. Prior commencement of actual work, it is necessary to define the map symbols. In general, existing map symbols will be used as much as possible if available. In the Study, map symbols were defined based on Dhaka Guide Map (map scale is 1:20,000). In case the scale of topographic map to be created and the reference topographic map for map symbols is same, it is possible to use the symbols of the existing topographic maps without any adjustment of size. However, in case the scale is different between the topographic map to be created and the reference map, it is necessary to adjust the size of map symbols to fit the image of topographic map to be created. In the Study, the size of map symbol for 1:5,000 scale digital topographic map was defined little larger than Dhaka Guide Map (1:20,000 scale) due to the reason of the difference of map scale. In case the existing topographic map is not available to define the map symbols, it is necessary to create new map symbols for topographic maps. In this case, the new map symbols have to easily imagine the planimetric features. The map symbols defined for the Study is shown in Figure 1.3.1 “Map Symbols Defined for the Study” and Appendix-2 “Map Style and Map Symbols for 1:5,000 Scale Digital Topographic Mapping (Version 2.0), June 2003”. - 4 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping Figure 1.3.1 “Map symbols defined for the Study” * The method of symbol definition in Microstation is the 4-1 page reference of Microstation User Guide. - 5 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping 2 DIGITAL MAPPING 2.1 Digital Data Acquisition The order of digital data acquisition is not decided. However, in general, the digital data will be obtained by the under-mentioned orders. 1. Road, bridge and railway 2. House and building 3. Fence, wall and so on 4. River, small river, lake and pond 5. Vegetation and hachure, etc. 6. Spot elevation 7. Contour line 2.1.1 Road, bridge and railway 1) National road, local main road It is recommended that the line of wide width road will be obtained one side by one side (not to use the parallel line). In case the line of road is obtained by parallel line by the judgment as same width on the photo image of digital plotter, the line of road and digital image may have discrepancy in some other location. 2) Paved and un-metalled road (width>2.0m) The paved road and un-metalled road will be judged by photo interpretation. In case the photo interpretation is difficult, the road within the city area will be judged as a paved road and the road in countryside will be as an un-metalled road. The Narrow two lines road is recommended to obtained by parallel line. The road means the lines between the road shoulders of both sides. These two lines will Seen like a wasteland. be obtained as the data of road Seen line a wasteland. Figure 2.1.1 “Road” - 6 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping Photo interpretation of un-metalled road that traffic vehicles are always running is easy due to the image of road is little white comparing less vehicles running unpaved road on the photo image. The road line will be obtained on the outside of wasteland running parallel with road. Photo interpretation of this wasteland is difficult and easily to miss-understand that the shape of wheel ruts is the edge of road and the both outside of wheel ruts are wasteland. 3) Road inside compound The road inside compound is the road with more than 2 m width and within the area surrounded by the fence and/or walls such as park, public facility and so on. In case it is difficult to judge, the road will be obtained as a normal road. 4) Under-construction road Under-construction road is the road presently construction is undergoing. The characteristic of under-construction road on the photon image is that the edge of road is ambiguous. The edge of under-construction road is not clear and the widths of under construction road become wide and narrow location by location. Therefore, the lines of under-construction road will be obtained by same width at the average width observed by zooming up of photo image of digital plotter. 5) Footpath The footpath with 50 m length (1 cm on 1:5,000 topographic map) will not be obtained. However, the footpath connecting between double line roads and footpath to village from the double line road has to be obtained even though the length of footpath is short. Village Double line road These footpath have Double line road to be obtained. Figure 2.1.2 “Footpath” - 7 - The Study on Urban Information Management for Greater Dhaka City Manual for Digital Topographic Mapping 6) Road under trees or tall buildings In the area of village covered by trees and city area with tall buildings, the road lines have to be obtained considering the connection of road alignment of adjacent area.