parcels
Cadastral Information Management with ArcGIS Christine Leslie Chris Buscaglia Kevin M. Kelly Tim Hodson
Agenda • ESRI & Geodata development Alliance • Introduction and Overview of software • System Design and Concepts • Demo • Product Release Information • Questions
2
UC 2006 Tech Session
Geodata & ESRI development Alliance •
Established in 2002
•
Overall Goals: 1. Design architecture for managing a parcel network in a geodatabase 2. Perform Adjustment of cadastral data using survey approach 3. Improve the spatial accuracy of cadastral data and feature layers
3
UC 2006 Tech Session
Geodata & ESRI development Alliance • Geodata’s role – Development of core adjustment engine – Provided the core Conceptual editing workflow
• Geodata & ESRI jointly defined XML format – seamless communication engine ÅÆ geodatabase – Data model
• ESRI’s role – Develoment of UI and the core geodatabase implementation
4
UC 2006 Tech Session
Introduction
This presentation describes the development work underway for the new cadastral editor for Survey Analyst – The Alice Project
5
UC 2006 Tech Session
What is The Alice Project ? ArcGIS 9.2 • Survey Analyst Product 9 Survey Editor
9Cadastral Editor
• Survey Analyst, product upgrade – Survey Editor (Built by Leica) – Cadastral Editor
• Release information after the demo
6
UC 2006 Tech Session
Motivation • Key layer in most multipurpose GIS is the cadastre • Extend GIS usefulness when spatial data is accurate and consistent • Optimize use of “survey” accurate coordinate information
7
UC 2006 Tech Session
GOAL of Alice Project
Build a simple system to: • Represent land record information in the GIS • Provide a core model for a LIS • Process GPS coordinates and land records together in a productive editing environment • Improve and maintain the accuracy of boundary geometry and associated GIS layers
8
UC 2006 Tech Session
GPS - An Important Driver
• GPS is now common-place • To fully exploit GPS Î – GIS must supply accurate underlying mapping information
• This was the weakness of GIS databases • Cadastral Editor can improve GIS accuracy
9
UC 2006 Tech Session
The Alice Project Requirements The system must:
10
•
Be Extensible (data model and tools)
•
Follow survey methods for changing geometry
•
Improve existing datasets
•
Maintain spatial relationships between the Cadastral base map and associated GIS layers
UC 2006 Tech Session
Survey measurements • Bearing and distance measurements used to be easier than directly coordinating a position • Survey measurement precision can be estimated by the date of survey • Land Surveys are recorded as deeds or subdivision plats of parcel dimensions • Parcels are defined by their relation to other parcels
11
UC 2006 Tech Session
Parcel corner coordinates • Measurements and connections are known, but true coordinates are not • So most Land Records in the U.S. have: – local coordinates with good “relative” accuracy – Measured ties to identified control
• But they typically do NOT have recorded coordinate positions
12
UC 2006 Tech Session
Existing LIS • Most LIS databases derived from scanning, digitizing plat maps and COGO • Accuracy poor even after “rubber-sheeting” to control • Original record measures are used for cartographic purposes only • Accurate geometry from COGO record information is distorted to fit pre-existing inaccurate data
13
UC 2006 Tech Session
What is a Cadastral Fabric? • A continuous surface of connected parcels • A dimensioned boundary network • Follows explicit constraints defined by common parcel corners and neighbors • Geometric constraints inherent in the model and validated during data entry
14
UC 2006 Tech Session
From Measures to Coordinates • Goal is accurate coordinates for the fabric and associated GIS layers • Accurate fabric coordinates are derived from: – geodetic control – Record data from survey measurements
• Like control, fabric points have: – A physical location via the monument – Accuracy information via the measurements
15
UC 2006 Tech Session
Advantages • Make a dimensioned cadastral fabric very accurate using limited control • Distribute error rigorously using a least-squares adjustment and all of the survey data - including historic • Hold derived coordinates as transient attributes • Retain historical coordinates
16
UC 2006 Tech Session
Fabric as Control for GIS • GIS feature layers often maintained in context with the cadastre • A positionally accurate cadastre then controls the GIS • By capturing coordinate shifts after adjustment – we can adjust associated layers and maintain spatial relationships
• The result is more accurate coordinates all around
18
UC 2006 Tech Session
System Design & Concepts
19
UC 2006 Tech Session
Simple data model
1 1-M 1
1-M
1
2-1 1-1
0-1 0-M
20
UC 2006 Tech Session
1-M
Simple data model
21
Parcel polygon
Parcel Line
has 1 – M Lines
has 2 Points
UC 2006 Tech Session
Fundamental design concept • Differentiate Source information from Derived information
GIS Rules
Survey Rules Edited only by Fabric Editor
Measurements From Survey (held by Lines)
22
UC 2006 Tech Session
Coordinates Computed (held by Points)
Topology may alter
ESRI Shapes Calculated from Points
Fabric as a Network • Parcels are the ‘unit of work’ – Create and edit parcels – Join parcels to the fabric
• Control points fix and georeference the fabric • Existing and historic parcels provide redundant measurements • Fabric network and control points are adjusted by least-squares
23
UC 2006 Tech Session
Parcel creation and editing • Enter a loop traverse of the parcel boundary • Parcels created in a local coordinate system • Parcel closure reported on-thefly
First Level QA check
24
UC 2006 Tech Session
Historical parcels • Parcels updated with new record information tagged as Historic • Historic parcels never deleted from the fabric • Four types of historic information maintained: – State of the Cadastre on a particular date, Legal Date – State of the Fabric on a particular date, System Date – Lineage of a Parcel – History of adjustments to the fabric 4 1
1985
25
UC 2006 Tech Session
4 6
2
3
1994
6
2
4
2000
7
Parcel Joining •
Merges local parcels into the existing fabric
•
Joining is an interactive ‘point and click’ operation 1. Match shared points 2. Automatic translation-rotation-scale
•
Simple 2D translation-rotation-scale: –
26
From local coordinate space Î To projected coordinate space (SPCS)
•
Q/C check using transformation residuals after Joining
•
Parcel Joining enforces the cadastral specific geometric constraints (topology) between parcels
UC 2006 Tech Session
Parcel Joining • Similarity transformation transforms un-joined parcel points • Residuals reported for each common corner • Accept or reject the join based on assessment of residuals Second Level QA check
27
UC 2006 Tech Session
Build fabric using Join • Rapid and simple way to build the fabric • Ensures fit to the existing fabric – Transfers basis-of-bearing – No slivers or overlaps possible
• Provides approximate coordinates needed by the leastsquares adjustment
28
UC 2006 Tech Session
Least-squares adjustment (LSA) •
Fabric + Control + LSA = Good Coordinates
•
More than improves coordinates 1. Shows where additional control is needed 2. Helps isolate errors in the data (e.g. incorrectly entered measurements)
•
Outputs post-adjustment analysis reports
•
Estimates coordinates only, never changes the original measurement values Third Level QA check
29
UC 2006 Tech Session
GIS Feature Adjustment • Using LSA results we create a set of adjustment vectors – An adjustment vector is the displacement between a point’s original coordinate and new coordinate after LSA
30
UC 2006 Tech Session
GIS Feature Adjustment
31
•
Store adjustment vector sets as a history of coordinate shifts based on each sequential LSA
•
Adjust (rubber-sheet) GIS layers using the vector sets:
•
Since the fabric maintains its adjustment “history” via the vector sets …
•
You can adjust a GIS layer to the fabric at your convenience
UC 2006 Tech Session
GIS Feature Adjustment
Utility line features incorrectly located with respect to the fabric…
Using adjustment vectors, utility line features are adjusted to the fabric.
What’s the RESULT? • A cadastral fabric that is: – Accurate to the same mathematical integrity of the original survey measurements – Complete by preserving all survey data – Coordinated in the NSRS
• A GIS database of original survey measurements • Correctly geo-reference GIS feature layers to the fabric • Keep apace with NSRS re-adjustments and epoch updates using least-squares adjustment 33
UC 2006 Tech Session
What’s the RESULT?
34
UC 2006 Tech Session
Components Cadastral fabric geometry + geodetic control coordinates + weighted least-squares adjustment + accumulated displacement vectors = ACCURATE FEATURE LAYERS
35
UC 2006 Tech Session
Demonstration
36
UC 2006 Tech Session
ArcGIS 9.2 Survey Analyst Product Release 9.2 Final Survey Analyst Product 9Survey Editor
9Cadastral Editor Beta
9.2 Pre-Release Survey Analyst Product 9Survey Editor
9Cadastral Editor Beta1
9.2 Beta2 Survey Analyst Product 9Survey Editor
Session Evaluations Reminder
Session Attendees: Please turn in your session evaluations. . . . Thank you
40
UC 2006 Tech Session
Agenda • ESRI & Geodata development Alliance • Introduction and Overview of software • System Design and Concepts • Demo • Product Release Information • Questions
2
UC 2006 Tech Session
Geodata & ESRI development Alliance •
Established in 2002
•
Overall Goals: 1. Design architecture for managing a parcel network in a geodatabase 2. Perform Adjustment of cadastral data using survey approach 3. Improve the spatial accuracy of cadastral data and feature layers
3
UC 2006 Tech Session
Geodata & ESRI development Alliance • Geodata’s role – Development of core adjustment engine – Provided the core Conceptual editing workflow
• Geodata & ESRI jointly defined XML format – seamless communication engine ÅÆ geodatabase – Data model
• ESRI’s role – Develoment of UI and the core geodatabase implementation
4
UC 2006 Tech Session
Introduction
This presentation describes the development work underway for the new cadastral editor for Survey Analyst – The Alice Project
5
UC 2006 Tech Session
What is The Alice Project ? ArcGIS 9.2 • Survey Analyst Product 9 Survey Editor
9Cadastral Editor
• Survey Analyst, product upgrade – Survey Editor (Built by Leica) – Cadastral Editor
• Release information after the demo
6
UC 2006 Tech Session
Motivation • Key layer in most multipurpose GIS is the cadastre • Extend GIS usefulness when spatial data is accurate and consistent • Optimize use of “survey” accurate coordinate information
7
UC 2006 Tech Session
GOAL of Alice Project
Build a simple system to: • Represent land record information in the GIS • Provide a core model for a LIS • Process GPS coordinates and land records together in a productive editing environment • Improve and maintain the accuracy of boundary geometry and associated GIS layers
8
UC 2006 Tech Session
GPS - An Important Driver
• GPS is now common-place • To fully exploit GPS Î – GIS must supply accurate underlying mapping information
• This was the weakness of GIS databases • Cadastral Editor can improve GIS accuracy
9
UC 2006 Tech Session
The Alice Project Requirements The system must:
10
•
Be Extensible (data model and tools)
•
Follow survey methods for changing geometry
•
Improve existing datasets
•
Maintain spatial relationships between the Cadastral base map and associated GIS layers
UC 2006 Tech Session
Survey measurements • Bearing and distance measurements used to be easier than directly coordinating a position • Survey measurement precision can be estimated by the date of survey • Land Surveys are recorded as deeds or subdivision plats of parcel dimensions • Parcels are defined by their relation to other parcels
11
UC 2006 Tech Session
Parcel corner coordinates • Measurements and connections are known, but true coordinates are not • So most Land Records in the U.S. have: – local coordinates with good “relative” accuracy – Measured ties to identified control
• But they typically do NOT have recorded coordinate positions
12
UC 2006 Tech Session
Existing LIS • Most LIS databases derived from scanning, digitizing plat maps and COGO • Accuracy poor even after “rubber-sheeting” to control • Original record measures are used for cartographic purposes only • Accurate geometry from COGO record information is distorted to fit pre-existing inaccurate data
13
UC 2006 Tech Session
What is a Cadastral Fabric? • A continuous surface of connected parcels • A dimensioned boundary network • Follows explicit constraints defined by common parcel corners and neighbors • Geometric constraints inherent in the model and validated during data entry
14
UC 2006 Tech Session
From Measures to Coordinates • Goal is accurate coordinates for the fabric and associated GIS layers • Accurate fabric coordinates are derived from: – geodetic control – Record data from survey measurements
• Like control, fabric points have: – A physical location via the monument – Accuracy information via the measurements
15
UC 2006 Tech Session
Advantages • Make a dimensioned cadastral fabric very accurate using limited control • Distribute error rigorously using a least-squares adjustment and all of the survey data - including historic • Hold derived coordinates as transient attributes • Retain historical coordinates
16
UC 2006 Tech Session
Fabric as Control for GIS • GIS feature layers often maintained in context with the cadastre • A positionally accurate cadastre then controls the GIS • By capturing coordinate shifts after adjustment – we can adjust associated layers and maintain spatial relationships
• The result is more accurate coordinates all around
18
UC 2006 Tech Session
System Design & Concepts
19
UC 2006 Tech Session
Simple data model
1 1-M 1
1-M
1
2-1 1-1
0-1 0-M
20
UC 2006 Tech Session
1-M
Simple data model
21
Parcel polygon
Parcel Line
has 1 – M Lines
has 2 Points
UC 2006 Tech Session
Fundamental design concept • Differentiate Source information from Derived information
GIS Rules
Survey Rules Edited only by Fabric Editor
Measurements From Survey (held by Lines)
22
UC 2006 Tech Session
Coordinates Computed (held by Points)
Topology may alter
ESRI Shapes Calculated from Points
Fabric as a Network • Parcels are the ‘unit of work’ – Create and edit parcels – Join parcels to the fabric
• Control points fix and georeference the fabric • Existing and historic parcels provide redundant measurements • Fabric network and control points are adjusted by least-squares
23
UC 2006 Tech Session
Parcel creation and editing • Enter a loop traverse of the parcel boundary • Parcels created in a local coordinate system • Parcel closure reported on-thefly
First Level QA check
24
UC 2006 Tech Session
Historical parcels • Parcels updated with new record information tagged as Historic • Historic parcels never deleted from the fabric • Four types of historic information maintained: – State of the Cadastre on a particular date, Legal Date – State of the Fabric on a particular date, System Date – Lineage of a Parcel – History of adjustments to the fabric 4 1
1985
25
UC 2006 Tech Session
4 6
2
3
1994
6
2
4
2000
7
Parcel Joining •
Merges local parcels into the existing fabric
•
Joining is an interactive ‘point and click’ operation 1. Match shared points 2. Automatic translation-rotation-scale
•
Simple 2D translation-rotation-scale: –
26
From local coordinate space Î To projected coordinate space (SPCS)
•
Q/C check using transformation residuals after Joining
•
Parcel Joining enforces the cadastral specific geometric constraints (topology) between parcels
UC 2006 Tech Session
Parcel Joining • Similarity transformation transforms un-joined parcel points • Residuals reported for each common corner • Accept or reject the join based on assessment of residuals Second Level QA check
27
UC 2006 Tech Session
Build fabric using Join • Rapid and simple way to build the fabric • Ensures fit to the existing fabric – Transfers basis-of-bearing – No slivers or overlaps possible
• Provides approximate coordinates needed by the leastsquares adjustment
28
UC 2006 Tech Session
Least-squares adjustment (LSA) •
Fabric + Control + LSA = Good Coordinates
•
More than improves coordinates 1. Shows where additional control is needed 2. Helps isolate errors in the data (e.g. incorrectly entered measurements)
•
Outputs post-adjustment analysis reports
•
Estimates coordinates only, never changes the original measurement values Third Level QA check
29
UC 2006 Tech Session
GIS Feature Adjustment • Using LSA results we create a set of adjustment vectors – An adjustment vector is the displacement between a point’s original coordinate and new coordinate after LSA
30
UC 2006 Tech Session
GIS Feature Adjustment
31
•
Store adjustment vector sets as a history of coordinate shifts based on each sequential LSA
•
Adjust (rubber-sheet) GIS layers using the vector sets:
•
Since the fabric maintains its adjustment “history” via the vector sets …
•
You can adjust a GIS layer to the fabric at your convenience
UC 2006 Tech Session
GIS Feature Adjustment
Utility line features incorrectly located with respect to the fabric…
Using adjustment vectors, utility line features are adjusted to the fabric.
What’s the RESULT? • A cadastral fabric that is: – Accurate to the same mathematical integrity of the original survey measurements – Complete by preserving all survey data – Coordinated in the NSRS
• A GIS database of original survey measurements • Correctly geo-reference GIS feature layers to the fabric • Keep apace with NSRS re-adjustments and epoch updates using least-squares adjustment 33
UC 2006 Tech Session
What’s the RESULT?
34
UC 2006 Tech Session
Components Cadastral fabric geometry + geodetic control coordinates + weighted least-squares adjustment + accumulated displacement vectors = ACCURATE FEATURE LAYERS
35
UC 2006 Tech Session
Demonstration
36
UC 2006 Tech Session
ArcGIS 9.2 Survey Analyst Product Release 9.2 Final Survey Analyst Product 9Survey Editor
9Cadastral Editor Beta
9.2 Pre-Release Survey Analyst Product 9Survey Editor
9Cadastral Editor Beta1
9.2 Beta2 Survey Analyst Product 9Survey Editor
Session Evaluations Reminder
Session Attendees: Please turn in your session evaluations. . . . Thank you
40
UC 2006 Tech Session
