Dr Craig Roberts UNSW

Transcription

1 Dr Craig Roberts UNSW The implementation of LandXML and datum modernisation are challenging authorities and surveyors. All agree that these are necessary changes but as we move past the conceptual stage and start to investigate the detail, more challenges emerge. In an attempt to grapple with this detail, a number of student thesis projects have been proposed. This presentation will cover 3 student thesis projects, the results from which demonstrate the relevance of spatial data in the digital economy.

2 The inevitability of spatial data in modern surveying practice: Investigations from recent student theses Dr Craig Roberts (Ahmed El-Kiki, Kathy Yan, Aaron Faull)

3 Software Ingestion of LandXML Files Ahmed El-Kiki

4 EPlan lodgment Creating LandXML files (Choi, 2017) Lodging LandXML files to LPI LandXML file stored by LPI Receiving existing files from LPI Courtesy Ahmed El-Kiki

5 LandXML ingestion (i.e. importing) TIFF plan LandXML File (adapted from Shojaei and Olfat, 2015) Ingested data Source: Google Images Courtesy Ahmed El-Kiki

6 Survey plan linework Plotted linework Linework geometry used to derive coordinates LandXML stores: Bearings and distances Coordinates Courtesy Ahmed El-Kiki

7 Courtesy Ahmed El-Kiki

8 My research Tested three surveying software: LXML4AC Stringer eplan 12d Model Determined problems associated with using coordinates Courtesy Ahmed El-Kiki

9 Simple Lot Experiment Tested LandXML for AutoCAD (LXML4AC) Courtesy Ahmed El-Kiki

10 Simple Lot Experiment CgPoint Coordinates Point Northing (m) Easting (m) Performed tests: Modified distance of Line 3 1 by 5m Modified bearing of Line 3 1 by 20 Modified CgPoint coord s of Point 3 by 10m in N & E Courtesy Ahmed El-Kiki

11 CgPoint coord s modified from (20,20) to (30,30) Inquired Distances & Bearings Line Inquired Distance Inquired Bearing Inquired = value determined using the software inquiry tools Courtesy Ahmed El-Kiki

12 Further software testing Courtesy Ahmed El-Kiki

13 Grid vs ground coordinates Deposited plans show ground distances Surveyors measure ground distances in the field Established survey marks show (MGA) grid coordinates The join between neighbouring grid coordinates gives grid distances Grid distances Ground distances Point scale factor at the Central meridian of a Zone = m Ground distance = m Grid distance = 400ppm!! Combined Scale Factor includes proximity to CM and height above ellipsoid How do surveyors deal with scale factor? How does LandXML deal with scale factor?

14 Grid vs ground coordinates Ground distance Grid distance Diagram courtesy ICSM GDA Tech Manual V2.4

15 Further software testing Tested more comprehensive file (simulated real file) Combined Scale Factor Control points (with MGA coord s) E N E N Tested additional software LXML4AC (re-tested) Stringer eplan 12d Model Courtesy Ahmed El-Kiki

16 Further software testing Repeated same tests as previous experiment: Modified distance of Line 3 1 Modified bearing of Line 3 1 Modified CgPoint coordinates of Point 3 Also tested: Modified MGA coordinates of SSM1001 Modified CSF of all connection lines Courtesy Ahmed El-Kiki

17 CgPoint coordinates of Point 3 modified from (20,20) to (30,30) Inquired Distances & Bearings Line Distance (m) inquired Bearing inquired Inquired = value determined using the software inquiry tools Courtesy Ahmed El-Kiki

18 Ingesting grid CgPoint coord s Distance difference between linework and LandXML file Ground distance (m) CgPoints Line created using GeoCadastre (not CAD software) - Can manually capture from DP - Adjusted by least squares to fit control - Control points adopted as fixed CgPoints in control datum (MGA) - Original 2 4 Brg/Dists of land 10 parcel retained and not adjusted by least squares Courtesy Ahmed El-Kiki file Grid distance (m) linework linework file

19 Summary Tested three software: LXML4AC Stringer eplan 12d Model Many problems with using CgPoint coordinates for LandXML ingestion Only bearings and distances from a LandXML file should be used Courtesy Ahmed El-Kiki

20 References CHOI, H. 12 September 2017a. RE: communication involving a few questions with eplan Project Officer. SHOJAEI, D. & OLFAT, H Victoria s journey toward eplan implementation and a 3D digital cadastre. Courtesy Ahmed El-Kiki

21 The Problem with Rendering LandXML Plans Written by: Kathy Yan (z ) UNSW B/Surv Program 3742 Thesis S Supervisor: Dr. Craig Roberts

22 NSW s Cadastre Monumented, vector-based cadastre ICSM s Cadastre 2034 goals: Sustainably managed Accessible and easily leveraged Linked rights, restrictions and responsibilities Models the real world Federated operation Currently requires submission of TIF and LandXML digital file formats Courtesy Kathy Yan

23 Pleco: Kathy s LandXML Renderer Created from scratch for the purpose of this thesis Written in Python 3.6 Open-source external libraries are used Shapely, a geometry processing library Pillow, an image drawing library Testing is performed with 16 LandXML files Courtesy Kathy Yan

24 Problems to Solve Direct Implementation: Plan rotation Drafting standards and annoyances Plans that will not render Discussion: Detail diagrams Collision Avoidance Courtesy Kathy Yan

25 Pleco Code (excerpt) """ PlecoRender Written by Kathy Yan for UNSW Surveying Undergraduate Thesis 2017 S2 "The Problem with Rendering LandXML" Supervisor: Dr. Craig Roberts Pleco is a LandXML renderer made to demonstrate possible improvements in existing LandXML rendering services. It is not meant to be used professionally in any way shape or form. """ # render all available plans for plen in getallplans(): # what shall i render today? me = selectplan(plen) tree = ET.parse(me) plan = tree.getroot() ns = '{ # parse landxml and assign data to classes cgpoints = cif.cgpoints(parser.parsecgpoints(plan, ns)) surveyheader = cif.surveyheader(parser.parsesurveyheader(plan, ns)) parcels = cif.parcels(parser.parseparcels(plan, ns)) monuments = cif.monuments(parser.parsemonuments(plan, ns)) # generate transformation parameters and transform coords to drawing space drawstate = drawingstate.drawingstate('a2', cgpoints, surveyheader, parcels, monuments, filename=me) drawstate.addpage(cgpoints, parcels) drawstate.dotransformations() drawstate.showpageproperties() # draw and save a simple DP rudimentary.crappyrender(drawstate) drawstate.savedp() Courtesy Kathy Yan

26 Plan Rotation Courtesy Kathy Yan

27 Rotation Find minimum bounding rectangle for all points Select longest edge of rectangle Rotate longest edge of rectangle to be horizontal Select the largest of the following as the scale: Divide longest edge of rectangle by horizontal space Divide shortest edge of rectangle by vertical space Courtesy Kathy Yan

28 Rotation Courtesy Kathy Yan

29 Drafting Standards Courtesy Kathy Yan

30 Drafting Standards Courtesy Kathy Yan

31 Symbol and line overlapping Draw symbols last Drafting Standards Extra dotted lines, superfluous information in tables, etc. Simply don t draw them (Unimplemented) Text rotation Consider plan rotation different to annotation rotation Courtesy Kathy Yan

32 Drafting Standards Courtesy Kathy Yan

33 Plans that will not render Courtesy Kathy Yan

34 Plans that will not render Courtesy Kathy Yan

35 Plans that will not render (cont d) Courtesy Kathy Yan

36 Plans that will not render (cont d) Courtesy Kathy Yan

37 Plans that will not render (cont d) Courtesy Kathy Yan

38 Collision Avoidance Courtesy Kathy Yan

39 Collision Avoidance Collision detection can be performed with bounding boxes and Shapely s intersects() method Collision avoidance can be performed by translation, rotation, scaling or a combination thereof. Courtesy Kathy Yan

40 Collision Avoidance Mockup Courtesy Kathy Yan

41 Conclusion The current LandXML renderer is improvable Many improvements are possible with time and effort Algorithms that can draw DPs better are uncomplicated Extensive testing should be done to identify where efforts should be focused Courtesy Kathy Yan

42 Georeferencing as Applied to Time Dependent Datums Aaron Faull (z ) Supervisor: Dr. Craig Roberts School of Civil & Environmental Engineering, UNSW, Sydney, Australia

43 Courtesy Aaron Faull

44 Source: Google Earth [3] Source: NearMap [6] Courtesy Aaron Faull

45 Source: University of South Florida [7] Source: Engaget [1] Courtesy Aaron Faull

46 Source: Your History Haven [8] Source: Getty Images [2] Source: ICSM [4] Courtesy Aaron Faull

47 Static Imagery Proposed Solution Source: Google Earth [3] Courtesy Aaron Faull

48 Courtesy Aaron Faull

49 Average Georeferencing Accuracy NearMap Google Maps Bing Maps 0.85 ±0.19 meters 0.41 ±0.44 meters 2.78 ±0.59 meters Courtesy Aaron Faull

50 Average Offset from GDA94 Average Offset from WGS84 NearMap 1.16 ±0.85m 0.41±0.85m Google Maps 1.44 ±0.41m 0.04 ±0.41m Bing Maps 5.09 ±2.78m 4.73 ±2.78m Courtesy Aaron Faull

51 Average Offset Average Offset from GDA94 from WGS84 NearMap 1.16 ±0.85m 0.41±0.85m Google Maps 1.44 ±0.41m 0.04 ±0.41m Bing Maps 5.09 ±2.78m 4.73 ±2.78m Courtesy Aaron Faull

52 To remain accurate throughout time; the necessity for orthophoto time dependent transformations is a function of the pixel resolution and magnitude of coordinate displacement between epochs. With the current accuracies of mapping products, applying time-dependent transformations won t be an important issue anytime soon. The offset between orthophotos and SPP GPS solutions due to continental drift is minimal in comparison to the offset caused from inaccurate georeferencing. Courtesy Aaron Faull

53 Concluding remarks Just finished a 2 year term as Education Rep on BOSSI The importance of LandXML and Spatial information for Surveyors is growing Surveying could be considered high accuracy Spatial Information Surveyors are comfortable with uncertainty misclose within regulations computer software often is not Rendering service for LandXML is problematic Coordinate accuracy from pixels on imagery relies primarily on georeferencing. Surveyors would not routinely trust this However modern imagery is hugely important for surveyors before, during and after their work