Cindy Lou McDonald
A rural county government GIS program (15,000 parcels) is mapping legal descriptions automatically by coordinate geometry. Four programs were considered, including ArcInfo, AutoCAD & other programs. The chosen program, created by the Emery County Utah GIS Specialist Lee Rasmussen, automates mapping with the ability to easily update parcel maps as section corners are resurveyed.
A Sample of A Carbon County Utah Plat Map
Carbon County is about 1500 square miles with a total county population of about 20,000. It was a great leap of technological faith for this small rural central Utah county to invest in a GIS Specialist, hardware and software.
The most valuable part of a rural county GIS database is the property parcel layer. It became clear that this county would not be satisfied in scanning or digitizing the current parcel maps. The County Surveyor and two local Title Insurance Company owners voiced frustration at the numerous errors in the current plat maps. They had no desire for us to just copy those errors digitally.
A joint meeting of the County Attorney, Recorder, Engineer and the Title Insurance Company decided that the GIS mappers should not arbitrarily close gaps and overlaps but to actually label and highlight them. They were adamant that the deeds had to be checked and the new parcels mapped from the deeds using our current best ability.
So began a three year search for a method to map our 15,000 parcels. We have had two Carbon County staff persons and four County contractors on our mapping crew testing and investigating our options for parcel mapping.
The Softwares Investigated for Parcel Mapping in GIS
Our mapping crew looked at the following softwares to assist in the effort:
The Guidelines Used to Choose a Software
We were looking for software to meet the following guidelines. With each guideline is an explanation of our experience with each software.</p>
The resulting data must be exportable into Esri ArcView where attributes could be added and links made to the assessing and recording database (ASCII files). The data must also be projected to State Plane (this is a Lambert Conformal Conic projection in central Utah). This projection is required and legistlated by the State of Utah for parcel maps. Also, the data must be georeferenced to North American Datum (NAD) 1983 with units in feet. The datum is also legislated by the State but the preferred units were changed by the Carbon County Surveyor since it would be more easily checked against current legal descriptions, which are in feet not meters.
The CAD files are notorius because they are not always georeferenced. However, Carbon County solved this problem by exporting our section corners from GIS to CAD .dxf before mapping was started. Then, all parcels were tied to their correct section corners as they were drawn. Resulting parcels are projected and georeferenced correctly.
In short, with some care, all softwares meet this criterion.
The parcel maps should contain two distinct themes for each piece of property--a spaghetti line file as mapped from the deed and a polygon file where parcels close at their beginning point. Gaps and overlaps are shown in both files.
ArcINFO COGO can create the polygons from the line file without using the "clean" command to eliminate gaps and overlaps between polygons. Polygons can also be created from CAD line layers. Cedra AVCOGO can use the ArcView Avenue script to convert polylines to polygons. Emery County COGO has its own program to create the polygons. So, although all programs use different methods of achieving this end, all softwares meet this criterion.
The resulting data should hold both the original legal description and the "mapped" description. Carbon County must create a "mapped" description when the legal description cannot be mapped as deeded (i.e. "to the tree where Uncle Fred shot the b’ar"). It is very important to leave a trail of mapped bearings and distances so the mappers assumptions and solutions can be justified or corrected in the future.
ArcINFO, CEDRA COGO and Emery County COGO can all hold this data in their respective INFO or dBase tables. A private contractor who mapped the parcels in CAD achieved this criterion by including an Access Database with the CAD drawings. The contractor then exported both files to ArcView and built a shapefile with an attached Dbase attribute table. All softwares meet this criteria although it is more awkwardly done in CAD programs.</p>
The resulting data should be exportable to ArcINFO where it can have topology built. ArcINFO COGO of course builds topology almost effortlessly. Cedra COGO and Emery County COGO also meet this criterion after some conversion. We have had some problems building topology CAD export files and on shapefiles created from CAD export files. All softwares can be forced to meet this criterion but ArcINFO is the most trouble-free.
The software must cost less than $3000 per seat. ArcINFO costs retail currently $18,000. AutoCAD LT as well as other inexpensive versions of CAD programs runs about $500. Cedra COGO cost $500 in 1996. The Emery County COGO package was generously traded for GIS services. All softwares except ArcINFO meet this criterion.
The software must be easily learned by persons with little or no computer experience.
Although initially intimidating, with customizable desktops, we have successfully trained people with little computer experience to map in AutoCAD LT; the Recorder's office using FastCAD had a similar experience and describes their work as "Fun!". Basic CAD programs can be learned from the documentation and there exists many CAD operators around the country so that extensive on-the-job training may not be required.
Similarly, ArcINFO is initially intimidating, but with the Utah County AMLs, staff can be trained in two weeks to COGO parcels. Still, it is advisable for any staff to take special ArcINFO training.
In 1996 our experience with CEDRA was that the poor documentation made the learning curve exceptionally complicated. A company sales person at that time recommended training at their offices in New York. This situation may have changed in the past three years.
The Emery County COGO program is easy to learn and takes care of many decisions behind the screen so that the operator does not have to make decisions better left to licensed surveyors.
In short, without excellent supervision or specialized training, ArcINFO and 1996 Cedra AVCOGO did not meet this criterion. The Emery County COGO program and the CAD programs meet this criterion.
The program should be able to automatically determine intermediate or missing section corners by taking an average of the existing section corners. Likewise, it should be able to automatically rotate parcel lines by proportioning the distance from the section lines so that parcels stay within the section.
The Emery County COGO package is the only software that meets this criterion. In addition it is possible in the Emery County program and with the Utah County ArcINFO COGO Amls to rotate some parcel lines and not rotate others. This is necessary because some parcels have been rotated (bearings such as N0*89’36"E are rotated already) while other parcels have not been rotated (a bearing of East has not been rotated). Rotation is required for accuracy but it is important to not rerotate parcels. Programs could be written for the other programs so that they can also meet this criterion.
The resulting data must be quickly upgradable as section corners are resurveyed. It should not be necessary to remap the entire county. This is the most important criterion of all. The cost and time to map parcels is so great, it is critical to never have to repeat the entire process again. The Emery County COGO package is the only software that meets this criteria.
Staffing Options for Parcel Mapping
Besides experimenting with programs, Carbon County GIS Department also ran a test to determine whether outside contracting or in-house contracting was the most cost effective for taxpayers.
To check the results of outside contracting, a bid was sent to about eight companies to map 1000 parcels. The resulting prices, received from five companies, resulted in a price range from $9.00 to $40.00 per parcel. The lowest priced company, after phoning references, was eliminated due to lack of experience. A contract was signed with an engineering and GIS company, Gateway Mapping of Orem, Utah at about twice the lowest price bid per parcel. The resulting contract was completed acceptably but the company indicated that future contracts might require a higher price since so many deed problems were encountered. Of course, the price per parcel may be lower if the parcels for an entire county were contracted. Also, although both the company and the contractor were careful to stay in close contact, to document decisions and to check and recheck methods, we were both surprised at the end of the project to discover a misunderstanding. This resulted in more work for both parties. COGO mapping is so complicated that it is difficult to control the outcome.
The average cost per parcel is running $10 each for local college students to work under contract in our offices. The job announcement requested high school or college students with good math skills who had completed some coursework or work experience in CAD or manual drafting. we knew better than to expect that students in our rural area would have even heard of GIS. The interview asked them to find the average of some numbers out to four decimal points and to identify a section on a USGS 7.5 minute topo map. In short, we were not requiring a high level of expertise. Carbon County has hired and trained three interns and Emery County has hired and trained another four interns. These students have surprised us with a shorter learning curve and higher than expected quality of work and problem-solving skills.
Carbon County’s experience is that in-house staffing or contracting results in more quality control at less cost than outside contracting. This may not be the best option for other counties since the supervision time can be significant and additional hardware and software must be purchased.
The Ten Steps of the Emery County COGO Program
The entire program runs from customized buttons on the view menu in ArcView 3.1. Users must copy the programs and scripts to a server or PC hard drive and create eight new buttons on the View Graphical User Interface. Carbon County operates the porgram on both Windows 95 and Windows NT operating systems. Also, a tiny critical file called Vbhome.txt must be copied to the root C: drive. This file can be edited to direct the program to run from any drive and any directory chosen by the user.
The two main program buttons are called REFORMAT and PLATPREP. The remaining buttons are scripts called LINE(L), POLYGON(P), TEMPLATE(T), SECTION 25(2), SECTION 81(8), and THREE LABELS(3). We will devote a section to each of these buttons later in this paper.
Step 1: Segregating, Researching and Cleaning the Legal Descriptions
Once we were ready to begin, the Carbon County Computer Department translated the entire Recorder's database from a proprietary format to ASCII text format as of a specific date. The GIS Department is responsible for mapping all parcels prior to that date. For changes made since then, the Recorder's Department will be responsible for the maps. All files have a common account number for each piece of property. There follows a sample of a "raw" legal description:
0069320 99 1001 1983
BEG 90 RODS N & 20 FT EAST OF SE COR OF SW1/4SW1/4 OF SEC 28, T14S,
SLM; TH N 13 RODS; E 1300 FT, S 13 RODS; W 1300 FT TO BEG.
The GIS Department then takes the legal descriptions and runs them through a cleaner. The cleaner was written by Mr. Rasmussen especially for the Carbon County files and removes extra words such as "of" and makes uniform the terminology, carriage returns, spacing and punctuation. The cleaner also deletes extraneous verbiage. Here is a sample of the cleaned descriptions. The only carriage returns are between records in this file:
0069320 BEG 90 RODS N & 20 FT EAST SE COR SW4 SW4 SEC 28,T 14 S,R 10 E;N 13 RODS;E 1300 FT,S 13 RODS;W 1300 FT TO BEG
Once the file is clean, mappers manually check the legal, cleaning up any items the program did not correct. These problems can be significant.
Sometimes the descriptions refer to a right-of-way or follow a wash. Sometimes description says "less parcel xxxxx". The deeds and mylar plats must be researched for a description. Sometimes a GIS vector file of a wash, road, railroad or a 1:24k digital raster graph might be viewed under the resulting parcel map so that a "mapped" description can be created.
It is hoped that scripts can be accepted by Esri to snap to intersections and endpoints. It is also hoped that return commands will be created in ArcView to return line bearing, much as commands are now available to calculate distance and area.
Currently, Carbon County mappers export the file to AutoCAD, snap to the necessary points, extract the bearing and distance of the lines created, then type that description into the ASCII parcel description file, substituting it for nebulous language in the "mapped" description file.
Once corrected automatically and manually, the resulting "mapped" description is renamed XMODATA and is ready to run the mapping program. An XMODATA file may look like the file below.
0069320, THERESA SANDERSON 020162199 BEG 1485 FT N & 20 FT E SE COR SW4 SW4 SEC 28,T 14 S,R 10 E;N 214.5 FT;E 1300 FT;S 214.5 FT;W 1300 FT TO BEG
The Recorder’s Office is trying to save time in the future by keying in new legal descriptions following the XMODATA format.
Step 2: Run Reformat Program
The program run next is called REFORMAT and results in a refdata.txt file. The REFORMAT program is accessed on the Carbon County GUI by a button bearing the "Execute" icon. The purpose of REFORMAT is to format the legal description to prepare it for x,y coordinate mapping. Mainly, REFORMAT puts the calls in a more logical sequence. The Traditional legal description format requires reading backwards. (i.e., se4nw4sw4 traditionally is found in a section by reading from right to left. REFORMAT turns the description around to sw4nw4se4 so the computer can read it from left to right).
It takes only seconds to run REFORMAT on a file of 40 or more parcels. However, there are usually errors in the legal description which must be corrected in XMODATA, then REFORMAT must be run again. The program also contains a Debugger that can be accessed via Visual Basic for easy troubleshooting. Debug can also be accessed via a text file. Errors can also be found by reading the Refdata or Closing error files or taking note of the place in the description file (XMODATA) where REFORMAT stops working.
A Refdata.txt file appears below.
020162199 THERESA SANDERSON 0069320
S28T14R10 BEG SW4 SW4 SE COR N1485F E20F THEN N214.5F E1300F S214.5F W1300F TO BEG
Step 3: Prepare Section Corner File
Platprep also requires a text file of section corners. This text file can be exported from an ArcView Shapefile attribute table, substituting a space for each comma delimiter. Emery County COGO expects three columns of space-delimited data: an ID number, X Coordinate and Y coordinate. The file must be named sur83s.txt and put under the GIS directory. A sample of the Sur83s.txt file follow:
1014600700 1849289.689 7039583.310
1014500700 1843980.461 7039507.629
1014400700 1838639.326 7039451.465
The Sur83s.txt file is one of the beauties of the Emery County COGO program. As section corners are resurveyed, the new x,y coordinates are substituted in this file. Reformat and PlatPrep are run again using the old, perfected XMODATA mapped description file and the parcels are tied to the new section corners. The first time parcels are mapped the most time-consuming labor is in researching deeds and correcting the XMODATA file. Since that corrected XMODATA file is archived, it takes minimal time to remap all parcels using new section corners or a new projection or datum.
Step 4: Run PlatPrep Program
The next program is called PLATPREP and results in a Linein.txt file, a Polyin.txt file and a closing error file. In the Carbon County GUI, PLATPREP is run with a button depicting the "New Program" icon. PLATPREP contains an option that will allow the mapper to rotate lines to run parallel with the section line. In the event that the section is trapezoidal, not square, PLATPREP will proportion all lines to run at an incremental bearing, depending on its distance between the two bearing lines between section corners.
The Linein file contains the spaghetti line descriptions for every line in the legal description. A sample follows:
2-162-199 , 1834771.244,7014223.397 , 214.5 '
2-162-199 , 1834769.836,7014437.893 , 1300 '
2-162-199 , 1836069.759,7014451.981 , 214.5 '
2-162-199 , 1836071.167,7014237.486 , 1300 '
The Platin file forces closure on all parcels and retains gaps and overlaps. The Platin file also contains the owner and parcel attribute information. A sample of the Platin file follows:
2-162-199 , 1834771.244 , 7014223.397 , THERESA SANDERSON 0069320 ,199
1834769.836 , 7014437.893 ,N 214.5 '
1836069.759 , 7014451.981 ,E 1300 '
1836071.167 , 7014237.486 ,S 214.5 '
1834771.244 , 7014223.397 ,W 1300 '
End, 6.4 Ac., DX, DY, Err = 0 0 0 0 Count= 1 07-20-1999 16:20 S28T14R10
Finally, the closing error file gives the bearing and distance of any missing closing legs in the polygon legal descriptions. Thus, if a legal description ends with a phrase such as "thence to a point 201 feet north of beginning; thence 201 feet to the pob" the closing error file will give the bearing and distance of the missing leg. A sample closing error file follows:
PARCELID DX DY XYErr @ Angle
2-162-199 0 0 0 @ 0 deg
2-162-299 -1.981 1.77 2.656 @ -48.2 deg
Step 5: Creating the Line Shapefile
Each of the remaining buttons are used to create a view from the legal descriptions. The Line (L) button creates a new shapefile called Line.shp in the same directory referenced when Platprep was run. The attributes include the parcel number and the bearing and distance of the lines mapped so they can be automatically labeled in ArcView. The program reads the Linein.txt file to create this shapefile.
Step 6: Creating the Polygon Shapefile
The Polygon (P) button creates the polygon shapefile called poly.shp from the platin.txt file. It will force closure on polygons that do not close properly but will not eliminate gaps and overlaps between parcels. The attributes contain the information from the XMODATA file, such as serial number, parcel number and owner name and it calculates acreage.
Step 7: Creating the Page Template
The Template (T) button creates a page template in the view complete with local section lines, page border, title and disclaimer notice.
Step 8(Optional): Creating the Sub-Section Line Shapefiles
The Survey 25-(2) button creates the section lines just for the section being mapped and gives lines down to the quarter-quarter section. Likewise, the Survey 81-(8) button creates the section lines just for the section being mapped down to the quarter-quarter-quarter section. These buttons are used mainly to assist in writing a mapped legal description. The program uses any available section corners, computes missing corner coordinates then connects them with polylines. The current attributes for the resulting Survey 25 shapefile include the distance and bearing in degrees-minutes-seconds. The current attributes for the resulting Survey 81 shapefile include the distance and bearing in decimal degrees.
Step 9: Creating the Plat Map Labels
The last button currently used by Carbon County is the Three Label button (3). This automatically labels the view with the owner name, acreage, and parcel & serial number of each parcel in the view.
Step 10: Print Map
The final step is a basic ArcView maneuver of creating a layout from the view and printing it. Carbon County overlays roads, railroads and watercourses on the plats and will underlay aerial photos of Digital Orthophoto Quads when they are completed by the U.S. Geological Survey in 2000. Carbon County has the Recorder and Surveyor check all new printed plats weekly then accepted plats are put into use.
In the next month we will change our process to include using the National Oceanic and Aeronautics Administrations new version of their Federal Geographic Data Committee-compliant metadata tool to document all decisions made during mapping (http://www.csc.noaa.gov/metadata/text/download.html). Currently, a text file is created of metadata but it does not meet the federal parsing requirements.
In the next six months, we will develop a method to regularly pull newly drawn parcels into ArcINFO to build topology and archive the data.
We will also create an automatic link updated weekly or daily with the Recorder & Assessor's database and offer complete parcel layers via the county intranet to all departments. This should occur within the next six months after we successfully install our new server and Internet Map Objects (a gift through the Esri rural governments program).
Availability of the Emery County COGO Program
The program is owned by Emery County, Utah. Requests for the program should be sent in writing to
Emery County Commissioners
C/o Lee Rasmussen, GIS Specialist
P.O. Box 907
Castle Dale, UT 84513
The Commissioners have decided to offer the executables to run the program at no charge to the 29 counties in Utah. They have also released the executables but not the source code, to:
1770 N. Research Parkway Suite 140
North Logan, UT 84341
InGEO has developed an Assessing and Recording software that is GIS based and indicated that they would be rewriting the source code for the program as a part of their package.
Carbon County found a uniquely appropriate method for mapping property parcels in the ArcView desktop-mapping program. It is inexpensive and has the ability to automate future remapping as section corners are resurveyed or projections are changed. The program should be of use for mapping parcels in the county for years to come since the initial investment of cleaning the legal descriptions for automated mapping will never have to be repeated again. The Emery County Utah COGO Program is the most useful and powerful ArcView tool we have found in our long search for an easy way to map property parcels.
Perhaps most importantly, the use of a file of section corners should be considered as a key element in all GIS databases. It can be assumed that section corner surveys will improve over the next 100 years. It can also be assumed that a great part of all GIS databases depend on section corner data. Such data would include all digitized data, all georeferenced images and all parcel data, to name only the major themes dependent on section corner surveys. Thus, database-driven GIS systems should program a mechanism for regular and automatic updates of the entire database as the x, y or z coordinates of section corners are resurveyed and improved. This will save millions of dollars in the future of remapping themes every time a new corner survey is updated.
Reference and Biography of Lee Rasmussen, creator of the Emery County COGO Program
Lee Rasmussen, author of the Emery County COGO Program was born, raised and attended high school in Ferron Utah. He completed a Bachelor of Engineering Science specializing in Electrical Engineering from Brigham Young University in Provo, Utah. Lee then completed a Masters in Engineering from the University of California at Irvine.
For 17 years Lee worked as a guidance and control engineer for aerospace projects at McDonnell Douglas. Monumental projects included writing scientific programs to put the first man on the moon, missile defense and an orbiting laboratory. He also worked for Utah Power and Light for 12 years as a performance test engineer.
After retirement in 1990, Lee went to work for Emery County as a computer programmer and now GIS Specialist. The codes for the Emery County COGO program took two years of development to write the source codes. The program has been in full production for two years and all plats are now completed in Emery County using the program.
Lee still refines the program on a daily basis, between his scuba diving stints to Africa, Papua New Guinea and the Marshall Islands. Last year he climbed the highest peak in the state of Utah, alone, starting at 3 p.m. after a day of driving to the trailhead. This author cannot decide if he is brilliant or addled.
Cindy Lou McDonald
120 East Main Street
Price, Utah 84501