Mapping And GIS Implementation
The collected data was transferred in a text file daily. This file contain x, y, z coordinates for each point. Text files also contained code of each item.
Fig.3: Coding system for collected data
All text files were prepared daily using the collected data for each day by using x, y, z coordinates. We developed an application for creating these text files. The macro transfers x, y, z and ID from field survey equipment, finds the district for each point and wrote that in text file. The text file names were the date of the day, such as 10NOV01.txt for the collected data on 10 November 2001. Mapping was performed with a macro under MicroStation. Macro reads x, y coordinates for each item from text file and drew all points automatically on the locations which are read from text file. An example for automated mapping and menu items of the macro given in Figure 4. The GIS contains two different type of graphic feature. These are:
- Lines for pipelines
- Points for catch base, groundwater, manholes and storm water manholes.
Lines, which represent pipes, are drawn by snapping the points by a house made automatic mapping application tool. We developed a tool for digitizing the pipes. Operator combines two manholes according to registered as built maps using this tool. By clicking the manholes all the information such as x,y,z coordinates, municipality name, district code, street code, manhole number extracted and are transferred to the proper fields in the database representing beginning and end points of pipeline. After clicking the end point, the length of the pipeline measured automatically and is written in length field of the database.
The slope of the pipeline is calculated using the length of the segment and `z coordinates of beginning and end points - depth of manhole` information of the segment.
The database contains for point feature below mentioned items
- ID - was taken from field survey code
- X - was taken from field survey
- Y - was taken from field survey
- Z - was taken from field survey
- Street names - was taken from field survey code
- District names - was taken from field survey code
- Municipality names - was taken from field survey code
- Type of item - was taken from field survey code
- Type (normal or exit)
- Maintenance date
- Maintenance type
- Maintenance period
- Depth of manholes
- Diameter of manholes and line code
- Net name
- Contract numbers
- Contractor name
The database contains for line features below mentioned items.
- ID
- Code
- Maintenance period
- Maintenance type
- Maintenance date
- Type of pipe
- Length of pipe
- Slope of pipe
- Invert elevation
- Diameter of pipe
- Line code
- Net name
- Contract numbers
- Material
- Contractor name
These features are collected in Ms Access database. In house developed macro reads the code from text file and creates the fields in the database and put the information in the database automatically. These fields are
- Municipality names
- District names
- Street names
- Types of items
- ID for each item
An operator using another macro in micro station simply links the other features for the points. By using this macro, after clicking an item, a data entry dialog appears and operator can enter the data for each item.
These data will be linked in Ms Access automatically. The data may also be
modified using this macro. The features that are entered by the operator are listed below:
- Maintenance date (date)
- Maintenance type (character)
- Maintenance period (character)
- Depth of manhole
- Type of manhole
- Diameter of the cover
All the ground and storm water maps compiled by Municipality were scanned. The Riyadh map and as built maps of municipality were registered and transformed by using the topographic maps that are compiled as part of project 116 of MOMRA and MOC roads, for digitizing of the pipelines. Pipelines were being digitized from these maps in MicroStation for the pipelines layer. These lines were guide for drawing line features of GIS. After creation of the line feature, user could link the data to the pipelines by using another macro. All the data that were linked by the operator were stored in Ms Access. The features, which were entered by operator, are listed below.
- Maintenance period
- Maintenance type
- Maintenance date
- Length of pipe
- Slope of pipe
- Type of pipe
- Diameter of pipe
- Type of facility
- Code of pipeline
The registered municipality maps were used as a guide for connecting the
manholes with pipeline lines.
After creating all the graphic features and the data, the delivery was made in the Intergraph Geomedia 4 format. The Geomedia file was created with geocoding of the database.
Fig.4: In house developed application for creating data and data entering-updating
CONCLUSION
The establishment of graphical and non-graphical database constitutes the most significant part of any GIS application, as much as 90-95% of the total investment. It is wise to utilize space technology to establish geo-referenced digital graphical (mainly orthophoto maps) database with the consideration of the short time and low cost. Since applications like facility management go down to the level of individual structure/parcel corresponding a map scale of 1/1,000 to 1/5,000, the minimum requirement expected from urban imagery is:
- 1m. or a better resolution
- ortho-rectification to have map precision (e.g.: 1/1000 to 1/5,000), i.e to produce orthophoto maps (Eren et al 2002)
IKONOS will play a very significant role as many countries have an intense need for detailed, accurate satellite
imagery for a multitude of important
applications, such as mapping, agricultural monitoring, facility management and urban planning studies.