Overview

Scripts

Folder: JavaScript Projections

• ProjInfoToCSV.py - takes Proj4 data from the output.txt file and converts it into ProjInfoRAW.csv. This file is then edited to create ProjInfo4.
• ProjInfoToDatabase.py - Gets the data from the ProjInfo4.csv and puts it into the database tables methods, parameters, etc. (run to setup database)
• CreateGridFiles2.py - creates the default projection grid folders and files in Archive/ProjectionGrids. This should be run first to setup the ProjectionGrids folder.
• CreateProjectionImages.py - adds the images for the web pages to the ProjectionGrids folder in Archive
• WriteOutProjInfo.py - writes out the ProjInfo and VarProjInfo files based on the current contents of the database

Old

• ProfileCreateImages.py - old file to do performance profiling of the image rendering code
• ProjectionToDatabase.py - old file to look at adding specific projections with parameters to the database
• TestAitoffLockUp.py - file to isoalate the lockup found in the Aitoff projection method

Folder: PythonGISApp

• GISApp.py - attempt at a GIS application in Python
• ProjectionExplorerIIQt.py

Utilities

• DialogSaveToDatabase.py - creates a dialog to save data to the database
• GeographicCanvasWidget.py
• PostgreSQLUtil.py
• ProjectedCanvasWidget.py
• ProjectionsDatabaseUtil.py

Old

• ShapelyContainsDefect.py
• TestWriteProjectionFile.py
• TimingTests.py
• UpdateCopyright.py

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Classes

SpaProjectorGrids is the top of the projection library.

Inheritance tree:

• SpaBase: Just stores settings (needed?)
  • SpaTransform : Not used?
  • SpaProjector: base class for projectors, defines project to and from geographic functions?
    • SpaProj: Implements projection with the Proj library, contains high level functions for projecting vector and raster data
      • SpaProjectorGrid: implements a grid-based projection based on proj projection coordinates
  • SpaProjectorGrids: Contains one or more SpaProjectorGrid for each of the unique areas that are needed to correctly project any area on the earth

SpaProjector

• ProjectFromGeographic(TheObject)

SpaProj

- Also defined in SpaPy library documentation

Projects from a source to a destination osgeo CRS

• SetSettings()?
• SetCRSes(FromCRS,ToCRS): Can pass in EPSG codes, proj params, or osr.SpatialReferences
• InverseTransformCoordinate (self,X,Y):
• TransformCoordinate(self,X,Y):
• Transform(self,TheObject)
• TransformRaster(self,TheObject,OutputFilePath)

Static functions

• TransformRaster(Input1,OutputFilePath,CRS1,CRS2=None)
• Transform(Input1,CRS1,CRS2=None)

SpaProjectorGrid

Settings

• GeographicBoundingBox
• DegreeSpacing
• "AreaDistortionMin
• AreaDistortionMax
• DistanceDistortionMin
• DistanceDistortionMax
• AdjacentAreaDistortionChangeMin
• AdjacentAreaDistortionChangeMax
• DistanceToCombinePolarCoordinates
• DensifyDistanceInDegrees":1, # None to disable densify

Member Functions

• SetSettings
• SpaProjectorGridInitialize(self):
• ProjectCoordinateFromGeographic(self,Lon,Lat,Elevation=0):
• GetAreaDistortions(self):
• GetBackProjectedGrids(self):
• SetParent(self,TheParent):

Private Member Functions

• GetOptimizedBoundsArray
  • _GetOptimizeddBoundingPolygon
    • SpaOptimizedBounds
    • _InsertPointsForFirstCellInNewBounds
    • _CheckCell()
      • _CheckCell_AreaDistortionOkay
      • FindAdjacentOutsideCells
      • _TargetCellValid
      • _CheckCellIntersectsWithBounds
      • _CheckDistanceDistortionForSides
      • _DeleteBoundsPoint
      • _MoveBoundsPoint
      • _SegmentBetweenPointsIntersect
      • _InsertBoundsPoint

SpaProjectorGrids

Settings (Additional on top of SpaProjectorGrid)

• "LongitudeShift":0, # Works the same as Longitude of Origin
  "LongitudeWestPad":0.00001,
  "LongitudeEastPad":0.00001
• SegmentIntersectionEndPointTolerance
• Debugging
• DumpCellsAsAdded

Drawing Settings

TheProjectorGrids.SetSettings(SpaProjectorGrids,ProjectorGridSettings)

1. Saves some settings as object variables

Setup

Sets up the projection engine,

1. Sets up the object variables:
   1. LongitudeOfOrigin: - always 0
   2. LatitudeOfOrigin: - 90 to -90
   3. LonNewPole: - 180 to -180
   4. .LatNewPole: - 90 to -90
   5. SpecifiedLongitudeOfOrigin: Original longitude of origin the user specified
2. Sets up parameters for proj
   1. Adds parameters except for lon_0
3. Initializes proj
   1. LatNewPole and LonNewPole are specified individuall as if these have changed from the defaults, the X transform will be called and passed the requested projection method.
4. Gets the geographic bounding boxes as a MultiPolygon geometry
   1. Initilze the grid projectors
   2. Get the grid projectors bounds in projected coordinates
   3. Compute OriginalProjectedBoundingBox
   4. OriginalProjectedBoundingPolys

Projecting

The approach is to (this is from SpaProjectorGrids.ProjectDataset():

1. Get the OriginalGeographicBoundingBoxes (may be shifted for longitude of origin !=0 )
2. Densify the dataset
3. For each ProjectorGrid
   1. Densify the dataset
   2. Get the ProjectedBoundsArray (this currnetly has just one entry)
   3. For each ProjectedBounds
      1. Get the Geographic Bouding Polugon
      2. Buffer(0) the polygon
      3. If ClipToFinalProjectedBounds
         1. For each GeographicBoundingBox
            1. Intersect the data with the GeographicBoundingBox (which may be shifted)
            2. Shift the data if needed
            3. Clip the data with the GeographicBoundingPolygon
            4. Densify the clipped data
            5. Project the data
            6. If this resulted in data,
               1. Buffer(0)
               2. Add to the new dataset
      4. Else
         1. Just project the data
   4. Return the array of datasets