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Georeferencing ERP Drawing Files

Georeferencing ERP Drawing Files. WMP Consultant Webinar – 25 August 2011. ArcGIS Skills: The GeoReferencing Toolbar Approximate Georeferencing Using 5 Point GeoReferencing Computing RMS error. SWFWMD Conventions: Filenames: ERP_XXXXXX_XXX_TYPE_Page_#.tif

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Georeferencing ERP Drawing Files

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  1. Georeferencing ERP Drawing Files WMP Consultant Webinar – 25 August 2011

  2. ArcGIS Skills: The GeoReferencing Toolbar Approximate Georeferencing Using 5 Point GeoReferencing Computing RMS error SWFWMD Conventions: Filenames: ERP_XXXXXX_XXX_TYPE_Page_#.tif ERP_XXXXXX_XXX_TYPE_Page_#.txt AsBuilt Approved_Plan WMP Consultant Webinar – 25 August 2011

  3. Raster Data – A Quick Review In its simplest form, a raster consists of a matrix of cells (or pixels) organized into rows and columns (or a grid) where each cell contains a value representing information, such as temperature. Rasters are digital aerial photographs, imagery from satellites, digital pictures, or even scanned maps. In raster datasets, each cell (which is also known as a pixel) has a value. The cell values represent the phenomenon portrayed by the raster dataset such as a category, magnitude, height, or spectral value. WMP Consultant Webinar – 25 August 2011

  4. The Effects and Georeferencing Toolbars Georeferencing is performed in ArcMap with the “Georeferencing Toolbar”. It is also convenient to use the “Effects Toolbar” during this process. Note: To activate these toolbars, you need to have a suitable layer in the TOC. In this case, you want a raster image (.TIF) in the TOC. WMP Consultant Webinar – 25 August 2011

  5. The Effects and Georeferencing Toolbars On the “Effects Toolbar”, use the: Contrast, Brightness , and Transparency slider tools to adjust the image. Once positioned, use the: Swipe, or Blink tools to evaluate the fit. Swipe Blink WMP Consultant Webinar – 25 August 2011

  6. The Effects and Georeferencing Toolbars Add Control Points View Links Table Three tools on the “Position” dropdown: Rotate Shift Scale The “Transformation” options are not available until the image has been Georeferenced! Note: The “Fit to Display” and “Auto Adjust” are checked on. WMP Consultant Webinar – 25 August 2011

  7. Georeferencing – The Quick & Dirty Method Step 1: View the image to georeference and determine an approximate real-world location. You may need to view the cover page to locate the ERP (or some other method.) Step 2: Add the necessary SWFWMD ArcGIS data to your ArcMap Document. You may need the Roads, ERPs, STR, etc. layers. Step 3: Add the appropriate year image to your ArcMap Document. You want to choose an image that POST-DATES your ERP. Step 4: Rotate your ERP image until north points “up” Step 5: In ArcMap, zoom into the real-world location so that your ERP will “fit your screen” Step 6: Rotate, Shift, and/or Scale the image until it fits Step 7: Check the fit with the Swipe and/or Blink Effects tools Step 8: Adjust as needed Step 9: On the Georeferencing Toolbar- “Update Georeferencing” Step 10: On the Georeferencing Toolbar – “Rectify…” (set all parameters) WMP Consultant Webinar – 25 August 2011

  8. Georeferencing – The Quick & Dirty Method (Q&D) For this Example, (ERP_001746_005_AsBuilt_Page_2.tif), I 1- Read the coversheet and found that the ERP was located in Sections 6 & 7 – Township 40S – Range 23E 2- Added the STR layer, the Streets, and 2007 image layers to my map 3- Viewed the ERP scanned image and rotated it until North was “up” 4- Using the selected STR, I zoomed into the general area and 5- Selected “Fit to Display” on the Georeference Toolbar 6- Adjusted the Transparency on the ERP scan image and scaled/shifted it into position. 7- Checked with the Swipe tool to make sure that things fit properly, 8- Used the “Update Georeferencing” to write the .TFW file. WMP Consultant Webinar – 25 August 2011

  9. Georeferencing – The Quick & Dirty Method (Q&D), con’t. To finish the Georeferencing, 9- Use the Georeferencing Toolbar to “Rectify…” and 10 – Fill-in the “Rectify | Save As” dialog as below. IMPORTANT: Cell Size < 0.25 NoData as “blank” Resample Type Output Directory Name as ERP Convention Format as TIFF WMP Consultant Webinar – 25 August 2011

  10. Georeferencing – The Quick & Dirty Method (Q&D), con’t. 11 – Add “Rectified/georeferenced ERP back into ArcMap and Review WMP Consultant Webinar – 25 August 2011

  11. Questions ???

  12. Georeferencing – The Accurate Method: GCPs We can use the “Quick & Dirty” method of georeferencing for getting the ERP into an approximate position. However, we need a measure of the accuracy of the rectified ERP. To get this measure, we will use Ground Check Points(GCPs). In this method, you need to identify at least 5 (five) points on the ERP scan that you can also indentify on the ortho-rectified aerial image. You can check your ERROR in identifying points after you select 3 (three) points. The goal is to rectify the ERP scan with the lowest Root Mean Square (RMS) error as possible. In general, the imagery has an accuracy of +/- 5’ or better, so an RMSe < 5’ is expected, and an RMSe > 10’ is not acceptable WMP Consultant Webinar – 25 August 2011

  13. Georeferencing – The Accurate Method: GCPs Note: Turn OFF the Auto Adjust option on the Georeference Toolbar As with the Q&D Method: Step 1: View the image to georeference and determine an approximate real-world location. You may need to view the cover page to locate the ERP (or some other location data.) Step 2: Add the necessary SWFWMD ArcGIS data to your ArcMap Document. You may need the Roads, ERPs, STR, etc. layers. Step 3: Add the appropriate year image to your ArcMap Document. You want to choose an image that POST-DATES your ERP. But now: Step 4: Closely examine the ERP scan for photo-recognizable points. These may be things like: road centerline intersections Centers of Cul-de-sacs Man hole covers Flood control structures WMP Consultant Webinar – 25 August 2011

  14. Georeferencing – The Accurate Method: GCPs, con’t. Step 5: Find those GCPs on the ortho-rectified image and record their real-world location coordinates (Northings and Eastings). Step 6: Zoom to the scanned ERP and using the Add Ground Control tool click the point(s) on the scanned ERP, right-click to open the dialog box, select “Input X and Y” and type in the real-world coordinate for that point. Step 7: Repeat Step 6 at least two more times. It is important that the first three GCPs be well distributed throughout the scanned ERP. It is best to have GCPs near each of the corners and one in the center of the scanned ERP Step 8: After at least 3 GCPs are input, select the “Update Display” to move the scanned ERP into it’s location. WMP Consultant Webinar – 25 August 2011

  15. Georeferencing – The Accurate Method: GCPs, con’t. Step 9: Set the Transparency ( and/or swipe) to determine where to place additional GCPs, or Step 10: Open the “View Link Table” to see the RMSe Step 11: If the RMSe is > 10’, add and delete GCPs until a satisfactory error is obtained, retaining a minimum of 5 GCPs at all times. Once a satisfactory RMSe is achieved, Step 12: Update the Georeferencing (as with the Q&D method), and To finish the Georeferencing, Step 13- Use the Georeferencing Toolbar to “Rectify…” and Step 14 – Fill-in the “Rectify | Save As” dialog as with the Q&D method. WMP Consultant Webinar – 25 August 2011

  16. Georeferencing – The Accurate Method - Example ERP Approved Plan to be Georeferenced: ERP 004863 000 Page2-Stewart Manor Subdivision SWFWMD Filename: ERP_004863_000_Approved_Plan_Page_2.tif WMP Consultant Webinar – 25 August 2011

  17. Georeferencing – The Accurate Method – Example con’t. I constructed an ArcMap document with the following layers: ERP Activity Area Section/Township/Range NAVTEQ Streets in the SWFWMD Searched in the “ERP Activity Layer” for ‘Base NBR’ = 4863 WMP Consultant Webinar – 25 August 2011

  18. Georeferencing – The Accurate Method – Example con’t. Note: In this case, there was a pre-existing polygon in the “ERP Activity Area” layer, and it has a geometry similar to the scanner ERP Drainage Plan. It also the correct “Permittee Name” (= Steward Manor HOA Inc.), so we can be reasonably certain that we have identified the correct area. To locate ERPs not in the ERP Activity Area layer (as applicable): 1- Rely on your personal knowledge of the ERP, or 2- Review the cover page(s) which will also be included in your working directory. These frequently have a location map, or 3- Examine the ERP for a PLSS identifier. Then use the Section/Township/Range Layer to locate the ERP, or 4- Find one or more road names on the ERP. Then “select” and zoom-to those roads on the NAVTEQ Streets in the SWFWMD layer, or 5- Type the name of the ERP into GoogleMaps (last resort), and pan around to find something familiar. 6- Ask others where in the world this ERP is located! WMP Consultant Webinar – 25 August 2011

  19. Georeferencing – The Accurate Method – Example con’t. 2 3 6 1 5 4 Having found the real world position of the ERP, I located 6 photo-identifiable points on the Drainage Plan WMP Consultant Webinar – 25 August 2011

  20. Georeferencing – The Accurate Method – Example con’t. 5 3 4 In ArcMap, mouse over the points and record the Northings and Eastings: 1- 1,391,630.43 x 510,188.55 2- 1,391,715.16 x 509,749.72 3- 1,392,198.19 x 509,758.21 4- 1,392,153.78 x 510,277.25 5- 1,392,271.31 x 510,239.51 6- 1,391,905.28 x 509,982.42 6 2 1 WMP Consultant Webinar – 25 August 2011

  21. Georeferencing – The Accurate Method – Example con’t. Zoom to the scanned ERP Zoom in to the area of a photo-identified point Use the GCP tool and click on the point, then right click and select “Input X and Y” Enter Coordinates (X = Easting; Y= Northing), press OK Repeat until all points are entered WMP Consultant Webinar – 25 August 2011

  22. Georeferencing – The Accurate Method – Example con’t. In ArcMap: Check that the correct target layer is set, and Select “Update Display” to move the scanned ERP to the real-world position. Open the Links Table and examine the RMSe WMP Consultant Webinar – 25 August 2011

  23. Georeferencing – The Accurate Method – Example con’t. After examination, it seems that Point #2 has a larger than expected residual, so by removing it, the RMSe decreases and I still have at least 5 points in the solution. WMP Consultant Webinar – 25 August 2011

  24. Georeferencing – The Accurate Method – Example con’t. To complete the process: SAVE the Link Table to: ERP_004864_000_Approved_Plan_Page_2.txt Use the Update Georeferencing Rectify… (using normal parameters) writing the georeferenced file to: ERP_004863_000_Approved_Plan_Page_2.tif in YOUR GeoTIFF directory WMP Consultant Webinar – 25 August 2011

  25. Georeferencing – The Accurate Method – Example con’t. In ArcMap: Add the newly georeferenced image Adjust its transparency (~65%) Check you georeferencing! WMP Consultant Webinar – 25 August 2011

  26. What to do when it just simply does not fit! • There are several reasons that after all this processing, • the scanned ERP just simply does not fit the image: • Spatial rectification error in the imagery • The ERP was modified in a subsequent revision • You misinterpreted a GCP coordinate • You mis-copied/transposed, etc. a GCP • The page (paper) was stretched over time • The page was badly warped during scanning • and it goes on and on … YOU have some control over #5 and #6 ! WMP Consultant Webinar – 25 August 2011

  27. What to do when it just simply does not fit! YOU control the Transformation used during Rectification The Transformation controls how the image is stretched: 1st Order – Linear Affine Transformation: shifts and rotates in a linear uniform manner 2nd and 3rd Order – fit to a polynomial- allows points to be shifted in a non-uniform manner. GOTTCHA: Need more (and more GCPs) for higher order Transformations WMP Consultant Webinar – 25 August 2011

  28. What to do when it just simply does not fit! The number of GCPs (parameters) needed increases as: T = Transformation Order, and GCP = number of Links GCP = (T+1)*(T+2)/ (T) WMP Consultant Webinar – 25 August 2011

  29. What to do when it just simply does not fit! So… For a 1st order Transformation, you need a minimum of : 3 (but we are using 5) For a 2nd order Transformaiton , you need a minimum of : (3)*(4)/(2) = 6 For a 3rd order Transformation, you need a minimum of: (4)*(5)/(3) = 10 … and the more the better! WMP Consultant Webinar – 25 August 2011

  30. Questions ???

  31. Some Georeferencing Dreams and Nightmares! Example 1 – The Ideal Case (almost): Good, clear corners that match the Parcel lines (ERP_015943_000_AsBuilt_Page_1) WMP Consultant Webinar – 25 August 2011

  32. Buildings corners fit well Other features fit well

  33. Example 2 – The not so Ideal Case: The drawing looks great, but the parcel lines do not match up well (ERP_003751_000_AsBuilt_Page_1)

  34. Parcels (Scan and ERP Activity Area) do not fit well But building corners fit!

  35. Example 3 – Nightmare #1: Drawing has great lines, BUT the project was MODIFIED so the site plan doesn’t match! (ERP_014233_001_Approved_Plan_Page_1)

  36. Site boundary and Parcel lines match well, but… Where’s the “Wet DetentionPond”?

  37. Example 4 – Nightmare #2: Isolated ponds with no external references (parcels, etc.)! (ERP_000071_008_AsBuilt_Page_1)

  38. The Drawing does not fit the ERP Activity Area (green lines), and … The pond limits do not fit the built pond!

  39. Example 4 con’t.– Nightmare #3: The ERP has multiple parts, spread over multiple sheets, and some have multiple parts on ONE sheet! (ERP_000071_008_AsBuilt_Page_3)

  40. Good luck finding that pond in this ERP!

  41. If you are “brave” (or just plain foolish) and want to try GeoReferencing any of these nightmares, we will be happy to ZIP them up and post to: http://ftp.sfwmd.state.fl.us/pub/outgoing/ GeoreferencingNightmares.zip WMP Consultant Webinar – 25 August 2011

  42. Georeferencing – Metadata The District will supply a Metadata template .XML file for use with georeferenced ERP images. The template was designed in ArcGIS10 and can be edited in ArcCatalog. It is the responsibility of the contractor to modify the following: Title Tags Description Credits Resource Identification Data Quality WMP Consultant Webinar – 25 August 2011

  43. Georeferencing – Metadata – Resource Identification WMP Consultant Webinar – 25 August 2011

  44. Georeferencing – Metadata – Data Quality WMP Consultant Webinar – 25 August 2011

  45. ERP Scanning and File Conversion The District uses a drum scanner to digitize ERP plan sheets into 300 dpi multipage Adobe™ Page Description File (.PDF) formatted files. The .PDF files are read with Adobe™ Acrobat Profession version 9.0 and Exported as Tagged Image File Format (.TIFF) files. NOTE: For ArcGIS to read the TIF file, the extension MUST be changed from .TIFF to .TIF WMP Consultant Webinar – 25 August 2011

  46. ERP Scanning and File Conversion The Export function will create one .TIFF file for each page in the original .PDF file. The user needs to supply an output location and filename, then choose the Settings… Note: If there are multiple pages, Adobe willname each page with the name provided as a filename below and will add the _Page_#.tiff to each! WMP Consultant Webinar – 25 August 2011

  47. ERP Scanning and File Conversion Choosing the settings as indicated will yield binary (0 & 1) monochrome TIF files that when queried with Windows Explorer Properties | Summary | Advanced, will reveal a BitDepth = 1: WMP Consultant Webinar – 25 August 2011

  48. Review of files So… When a WMP Consultant returns a georeferenced ERP image to the District, the following files should be included: 1- The ORIGINAL .PDF file (properly named) 2- The GEOREFERNCED .TIF file (properly named) 3- The GROUND CONTROL .TXT file (properly named) 4- The METADATA .XML file (properly named) EXAMPLE: ERP_000071_000_AsBuilt.pdf (one may apply to several pages) ERP_000071_000_AsBuilt_Page_2.tif ERP_000071_000_AsBuilt_Page_2.txt ERP_000071_000_AsBuilt_Page_2.tif.xml WMP Consultant Webinar – 25 August 2011

  49. Questions ??? Stay tuned for HEPs coming up next!!!

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