Priemere Power. Geodetic Assistant

Transcription

1 Priemere Power Geodetic Assistant A custom Add-In (extension) to Educate & Inform the ArcGIS User by: Rich Priem Rich@Priemere.com APSG-30 Conference September 25, 2013

2 Awarene$$ Messsages $ignificant financial risk$ 2 /20 Reference: APSG-29 Barnes & Salvage

3 Geodetic Education 3 /20

4 Objectives 4 /20 Target: ArcGIS Desktop Users Consumers of Spatial Data, not Surveyors But also using to generate Spatial Information Education No time or interest to learn geodetic details Map makers, not mathematicians Just-in-Time Information Alerts when risking mistakes Details to help make better decisions

5 The Problem in ArcGIS 5 /20 Transformations Hard to Find Notice that Button? Simplistic Interface Little Information Help not working? Available Options NONE is the Default!!! Meaningless Names Just a numeric suffix Cancel: the expedient path of least resistance Caribbean!!! Canada, western Canada, central Canada, eastern Canada, northern

6 Alerts could be more Helpful 6 /20 Triggers Change Map Datum Add Data to Map Not Document Open? Will Likely! Warning too Subtle What is Probability or Magnitude? Easy to Ignore Standard legal CYA disclaimer? Difficult to Restore Can you find the EXE on C drive? Why not a button from Options menu? HKCU\Software\ESRI\Desktop10.0\ArcMap\Settings\SkipDatumCheck

7 A Message of Magnitude 7 /20 Hundreds of feet or meters Typical shift between different datums Transformation required to handle correctly Tens of feet or meters Typical difference in available transformations Several feet or meters Typical accuracy with correct transformation Spatial Uncertainty Can be understood from above choices Do Something: nothing likely the worst choice!

8 On the Fly Projection 8 /20 Integration Powerful functionality to build complex maps Facilitates combining many disparate data Dangerous Requires clear definition of coordinates Transformations: particularly problematic Examples: increasing spatial error or uncertainty Viewing map with mixed projections & datums Digitizing or drawing new data on top of that map Output results from calculations on mixed data Exporting Data in Map Coordinates (locking in) Publishing to App that requires single coordinate system

9 Too Many Options 9 /20 EPSG Registry: unique Datums 2065 Transformations (395 deprecated) ArcGIS supported Transformations (half above) 321 unique Datums (60%) 437 source/target pairs to Transform, only 1.36 per source Dichotomy Most datum pairs have few transformations Average of 2.25 per available pair Some datums have very many transformations 295 for WGS-84, arguably the global standard 33 for ETRS-89, 12 for WGS-72, 11 for NAD-83

10 Resources to Leverage 10 /20 EPSG Geodetic Registry Geodetic Parameter Dataset Coordinate Reference Systems (CRS) Projections (PRJ), Datums (GCS) and Transformations Details: name, vintage, scope, accuracy, parameters Area of Usage Rectangular extent: available long ago Polygon Outlines: released ~4Q12 Priemere Ingenuity Lets put it all together...

11 The Solution: Information 11 /20

12 Alerts and Options 12 /20 Triggers Open Document Change Map Datum* Add new Data* Zoom below scale threshold Save Document Nuisance Factor *Redundant with ArcGIS Try to find Balance Defer if really too busy Easy or Automatic options as alternative?

13 Usage Polygons 13 /20 Overlap Percentage Start with current Map Extent Intersect with Polygon Percentage of original Map Extent Use to Subset & Prioritize Suggestions Shift Statistics Generate a set of sample points currently: 11*11 grid inside map extent Convert from Target coordinates to Source datum Calculate the distance and angle of shift Generate statistics Mean, Min, Max, Median, Azimuth, etc.

14 Supporting Statistics 14 /20 Example: GoM Basin Frequent Problem Map: BLM-15, NAD-27 Data: WGS-84 Sorted Options 84 Transformation Flash: to confirm footprint 15 Overlap AOI Statistics 34% for Active 65% for Largest Shift is average of 14 feet 11 degrees NNE Range is 32 feet (uncertainty)

15 Source Layer Details 15 /20 Tree organized by Coordinate Systems Hierarchy: Datum, Units, Projection, etc. Context menu to Repair (beta) Remove from Map Fix Broken Links Change to Inherit Map Datum Map Projection

16 Free Download 16 /20 AGO: ArcGIS Online Gallery: search for Priemere Check Show Desktop Content Open: simple download & install of Arc10 Add-In 1 2 3

17 MetaData Integration 17 /20 Priemere Power Tools for ArcGIS The Petroleum extension for Data Access, Risk Analysis, and other G&G work flows MetaData Lineage: history of ancestors Trying to convince ESRI to Adapt... Captured for every GIS output dataset Inherit an appropriate subset of parent metadata Viewer to display resulting Hierarchy Coordinates Source Target Transform

18 Other ArcGIS Observations 18 /20 ArcMap Just one transformation is automatic default NadCon for Nad-27 to Nad-83 in continental US <None> is not valid from dialog Can not undo once something is set? Alert suppressed when adding data to new map Coordinate System is inherited after adding data Arc Scene Transformations not supported? Not in Coordinate Dialog, nor under the hood in Arc Objects Arc Globe Coordinates are always WGS-84 Transformations appear to be supported

19 Progress in ArcGIS / : Version 10.0 Clients only recently starting to migrate 2012: Version 10.1 Introduced Compound Transformations Many more choices to digest Names are even longer, but still meaningless. 2013: Version 10.2 Search added to Property Page Subset & Sort Transforms by Extent None is valid again? Globe will automatically set to the top item Good idea for Arc Map as well?

20 V3 Enhancements 20 /20 Alerts Balancing the Nuisance Factor Statistics Validate calculations of Shift Eliminate active Transformation from Results Packaging Stress Testing all of the Options Documentation Improvements Tool Tips on Tables Context Menus Expanded

21 Way Forward 21 /20 Free Download Spread the Word... Questions Answers Comments or Feedback Concerns to Address? Enhancements to Consider Contact: Rich Priem +1 / Rich@Priemere.com

22 Bio: Rich Priem 22 /20 Rich is a GIS Expert & GeoScience Consultant with degrees in Engineering, Mathematics, and Computer Science. He has been running the Priemere Consulting Group for more than a quarter century, with significant experience at Exxon and BP/Amoco. Over the past decade, he has been dedicated to evolving the Petroleum Extension for ArcGIS, with corporate licenses at many of the larger companies in the Exploration industry.

23 Abstract 23 /20 Geodetic Assistant to Educate the ArcGIS User By Rich Priem, Priemere GeoTechnology How does the casual ArcGIS User avoid making basic positioning errors? The PUG User Community has heard doom and gloom, long and loud. And there are plenty of training classes offering PhD thesis in mathematics, for those that have the time and interest. But still, the majority of Users remain blissfully ill-informed, and routinely click CLOSE when receiving the Geographic Coordinate System Warning, or when attempting to select the appropriate Transformation from a long list of names that are all the same except for a simple integer suffix. The EPSG Registry provides much more extensive information, but who knows how to find, yet alone navigate through 538 different datums and 2065 associated transformations? Our solution is the Power Geodetic Assistant, which we currently offer as a free download from ArcGIS Online. This custom extension provides more extensive alerts when issues are identified, and an interactive form to review the options and make appropriate selections. Included is the ability to view attributes from the EPSG Registry for all relevant transformations, and flash the polygon representing the usage area for a specific transformation. Furthermore, there is an interactive list of layers that would be affected by the transformation, and detailed statistics to quantify the amount of shift that will occur. Finally, for those that still don t have the stamina to investigate, there is an Easy button to apply our suggestion, determined from the intersection of the data with the usage polygons.