POEC 6387 GIS Workshop Project


Project Objective
Hardware and Software Used
Data Sources
One Point of Interest
Accuracy Issues
The Finished Product

Project Objective:

Number 15 on Dr. Briggs Potential GIS Projects. "Create historical city boundary coverage's for one city." In this case the City of Dallas, annexations by decades from 1940 through 1990. After talks with planning department staff I decided to make the project more of a challenge by creating a separate map that would identify some of the ordinance annexations/deannexations after 1940. To clarify, the ordinance map like the decade maps will only be a good representation, as both were not derived from legally binding documents such as deeds, etc.

Hardware and Software Used:

  • Pentium CPU, MS Windows NT version. 4 OS,
  • ESRI Arc/INFO ver. 7.1.2, Arcview version 3.0a
  • Bentley Microstation95
  • Corel Photo-Paint version. 5.0

    Data Sources:

    City of Dallas, Planning Dept.

  • Annexation Maps - Hard Copy

    City of Dallas, Water Dept.

  • Old utility maps - Hard Copy
  • Lake Ray Hubbard Boundary map - Hard Copy

    Dallas Central Apprasial District

  • Current version of Dallas County Abstract map - vector format

    North Texas GIS Consortium Data Files

  • 1994 and 1997 Street centerline, Railroad centerline, and Hydrology - vector maps

    1998 Mapsco


    1. Copy city boundaries from Wall maps in City Planning department to Consortium street centerline maps plotted out for drawing on. Copy line for line from the hard copy maps by digitizing line after line into a CAD drawing. Because data resides on larger than 34x44 (E size) wall maps, and 8.5x11 Ordinance descriptions, Digitizing was completed using Microstation CAD software.

    2. Converting the digitized CAD file into Arc/INFO. CAD offers the easiest solution for monotonous, tedious, daunting digitizing and Arc/Info is a great QC tool for identifying overshoots and undershoots and missing lines.

    2A. Commands used at the Arc prompt

  • :igdsarc in_igds_file out_cover

    Arc: igdsarc dalbnd12.dgn dalbnd12

  • :build cover line

    Arc: build dalbnd12 line

  • :clean in_cover {out_cover} {dangle_length} {fuzzy_tolerance} (line}

    Arc: clean dalbnd12 dalbnd12 2 2 line

    2B. Commands used in Arcedit to further clean up over/under-shoots, and obvious missing arcs

  • edit coverage dalbnd12

    Arcedit: ec dalbnd12

  • draw environment arcs nodes node errors with the dangle symbol

    Arcedit: de arc node node error dangle

  • make the nodecolor dangle color red

    Arcedit: nodecolor dangle 2

    Arcedit: draw

  • Set the nodesnap for the closest node

    Arcedit: nodesnap closest *

  • Then extent into every area where a red square symbolizes a node error and fix accordingly. Once every error is corrected then quit out of Arcedit to the arc prompt and build again.

  • : build cover {line}

    Arc: build dalbnd12 line

    2C. Once overshoots, undershoots, and missing lines are resolved build polygons

    Arc: build dalbnd12 poly

    3. I completed step 2 for my ordinance cover (dalord) and built polygons.

    3A. I had to create a character item called ordinance# in my cover.pat table (dalord.pat). Character; because some of the ordinance numbers are longer than four (4) digits.

    3B. I attempted to hard code each ordinance# by using the calculate command in Arcedit, when Arc decided to crash, with the result being jumbled numbers. Luckily I was in my second day and had saved my cover as a shapefile the day before.

    3C. I then started adding ordinance numbers by hard coding them into each polygon record using Arcview and would recommend this over the Arcedit calculate command. Another reason for this decision was the fact that city planning would be using Arcview to correct and add more ordinance information to my deliverable.

    4. City Planning had an existing spreadsheet identifying ordinance-related information that I attempted to join with my shapefile table.

    Convert the spreadsheet information into a text file and add it to my project in Arcview. Once added I coverted it into a DBASE file. Another problem arose when duplicate ordinace numbers where found in the DBASE file. When the city adopts tracts of land they can include many tracts or parcels under the same ordinance number. The unique identifier for each tract or parcel could be a block number, tract number, or a lot number. So knowing that the city would resolve this problem with the implementation of a database management system I would not alter anything other than adding a field called tract to help split the most obvious duplication problems. For example ordinance number 3626, passed May 16, 1945 included twenty two (22) separate tracts of land in every part of the city, and in the spreadsheet the unique identifiers where included in a description of what was adopted.

    5. Convert vector maps to raster images.

    Software Used: Arcview ver. 3.0a, and Corel Photo-Paint ver. 5.0

    Procedures in Arcview:

    5A. add map shapefiles in the view screen of Arcview Project.

    * In my case I had saved my Arc covers as Arcview shapefiles. dalbnd12.shp, dalbnd22.shp, dalbnd40.shp....etc....

    5B. Make a Layout of the View screen.

    5C. Export Layout to a Windows Metafile.

    * I would be using Corel Photo-Paint just because!; so I had to experiment with all the image options in Arcview. I had trouble with Placeable WMF because my image came out twisted 180 degrees upside down. I also had difficulty dealing with Windows Bitmap images in Corel, and finally no luck at all with EPS and CGM formats. EPS and CGM could not be opened in Corel.

    Steps taken in Corel Photo-Paint:

    5D. Open the image in Photo-Paint.

    * dalbnd12.wmf

    5E. Save the image as a JPEG, then make necessary changes to the JPEG image.

    * For exmaple I had to redo the Title Block and Legend text in all my images due to the translation from one format to another. When looking at the map images compare the street names with Title Block and Legend text.

    6. Set raster images into my website. How do you do this? Learn html by checking out Dr. Briggs website.

    7. Hand data over to City of Dallas, Planning department and UTD. Both use Arcview and the standard CAD package used for Mapping in most City departments is Microstation. As a result of these considerations, the final deliverable of my project came in both Microstation CAD format(dgn), and ESRI ARCVIEW Shapefiles. Remember that MICROSTATION (dgn) CAD files can be used in Arcview 3.0a and AutoCAD (dxf) CAD files can be used in Arcview 3.1


    One point of interest !

    I had been in contact with staff in the Planning department since May, and finally in July after time to think about the product of this project, I was asked the Magic question...

    Who will maintain this data ?!


    Accuracy Issues


    The Finished Product

    Click here to see the Decade Maps

    While scouring through the planning department, I was also able to find boundary maps for 1912 and 1922.

    1912 1922

    Click here to learn more about GIS

    return to my home page

    08.06.98 RGD