3D feature collection for ArcGIS

3D feature collection for ArcGIS

• 1.
  Precise 3D featurescollection inside ArcGIS with photogrammetry and LiDAR GEOSOFT srl – Pordenone (ITALY) www.geosoft.it [email_address]
• 2.
  Currently the mostpopular method to... acquire update verify ...geometric data in a GIS is based on use of the orthophoto GIS (Geographic Information System) require more precise, reliable, updated data… Buildings : how to measure the height? where is the correct position ?
• 3.
  The use oforthoimages has some advantages… Is a bidimensional activity… thus the digitalization is fast and very simple… Does not require both specific hardware and software But… Require a DTM thus is most expensive respect the images which derives Introduce new errors related to the DTM (grid/TIN approximations, acquisition time etc…) Some entities does not refer to DTM (buildings, bridges etc…) in this case the height information are lost The 3D position of these objects is not accurate (principally due to perspective error) and sometimes it is not even acquirable Mapping and/or photointerpretation of some objects is very difficult (orthophoto is only bidimensional)
• 4.
  First solution Usethe stereoscopy for photointerpretation and or mapping… What we need Images (aerial or satellite) with internal and external parameters Software for image orientation (Automatic or manual Bundle Block Adjustment, GPS/INS support etc…) - OPTIONAL Hardware for the stereoscopic visualization (for example IZ3D stereoscopic monitor, nVidia 3D Vision ® , Planar ® , True3Di ® ... price start from 600 Euro )
• 5.
  Benefits 3D accuracyhigher than with orthophotos… XYZ position doesn’t depend on object height or DEM accuracy Photointerpretation “is more natural” and simple Hardware for stereoscopy is LOW COST ( thanks to gaming and entertainment industry ) Problems Require more skilled operators (stereoscopic perception) for Z position Solution: LiDAR (next slides…) 2D objects are a problem in super-imposition (typical in GIS data) Solution: Extract height information from feature database fields (optimal if constant) and/or from terrain input layer like grids or 3D features (optimal if not constant)
• 6.
  ArcGDS example 1“Photogrammetry only” demo Start presentation
• 7.
  Photogrammetry main problem Requires stereoscopic perception capabilities of the operator for a precise and reliable Z Solution: LiDAR (Light Detection and Ranging) which is an optical remote sensing system used for the generation of digital terrain and surface models (DTM and DSM) Geosoft solution in ArcGIS environment is… ArcGDS LiDAR adds to ArcGDS the capability to get automatically the third dimension of the objects from the LiDAR points cloud
• 8.
  LiDAR data canbe imported in various ASCII format files… For example: X Y Z Range X Y Z Class X Y Z Red Green Blue or a combination of these… NOTE: Cloud coloration by class, range, intensity, aerial images Don’t need DEM, DSM, grid... But only the POINT CLOUD !
• 9.
  Photogrammetry alone isnot enough… Optimal photointerpretation (image data is continuous) Use of RGB, CIR images with 8+ bit per channel Already experienced operators, well known procedures and system New digital cameras have bad B/H ratio (respect to the LiDAR data at the same flight height) Data quality is not geometrically constant (Z in particular) because depends on the operator (stereoscopic perception) Image correlation often have problems exactly where we need (for ex. roof edges)
• 10.
  LiDAR alone isnot enough… Optimal precision (especially Z) respect to the photogrammetry at the same flight height Possibility to classify the points cloud Data quality is geometrically constant (Z in particular) because does not depend on the operator (snap) Data have low costs and short acquisition times Interpretation is very poor because the data is discrete Point density impact a lot on cost The points don’t have directly the color of the objects XY precision is poorer than Z
• 11.
  Characteristics of ArcGDSLiDAR method (patent pending) Production of 3D geodatabases with high quality Photointerpretation (photos) is available LiDAR acquisition allow much better precisions than photo-mapping or orthophoto digitalization Mapping (for ex. streets or buildings) is coherent with LiDAR Operator checks Z during mapping and eventually changes it manually Is for everybody because not require a high photogrammetric knowledge Snap uses cloud classification Transversal profile view helps operator for a better interpretation Operator must control contemporary many windows Data intensive computing... (require a modern 500 Euro PC !!!)
• 12.
  ArcGDS example 2“Photogrammetry and LiDAR” demo Start presentation
• 13.
  Supported hardware forstereoscopic vision CRT Monitor + Z-Screen ® with passive polarized glasses CRT Monitor + CrystalEyes ® with shutter glasses LCD 22” iZ3D Monitor ® with passive polarized glasses (800 Euro with graphic card) LCD 22” Monitor + nVidia 3D Vision ® with shutter glasses (1200 Euro with graphic card) PLANAR ® Monitor with passive polarized glasses TRUE3Di ® Monitor with passive polarized glasses Virtually any other OpenGL quad buffer compatible stereoscopic device Supported hardware for 3D pointing Mouse and scrolling wheel (for Z) Mouse and trackball (for Z) Stealth 3D mouse ® (with USB interface) Immersion SoftMouse ®
• 14.
  Supported sensor modelsAnalogic frame camera Digital frame camera, for ex. Z/I DMC ® , Vexcel UltraCAM ® etc… Leica ADS40 ® pushbroom Satellite images with RPC camera model Supported LiDAR file format ASCII files with X,Y,Z,… LAS binary files Supported image formats (used in native way) TIFF (8,16 bit for channel) ECW ® (Enhanced Compressed Wavelet by ERMapper) JPG2000 (8,16 bit for band with 1,3 or 4 bands)
• 15.
  Conclusions Stereoscopy isfor avaiable for all the users at low cost, inside ArcMap Aerial images are better than orthophotos (more precise, less expensive) LiDAR point clouds can aid the users (high Z precision, more productivity)
• 16.
  For further informations: www.geosoft.it/gds/arcgds [email_address] Aldo Facchin GEOSOFT srl – Pordenone (ITALY) [email_address]