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#Xlist location code#

BinarySearch ( searchValueLat ) Dim indexX As Long = XList. GPoint 'Point Mapping function: Input (LatLng), Output (Best pixel-location on map) 'Needs precalculation of Pixel-LatLng-grid (Sub: precalcValues) Dim indexY As Long = YList. 'Sorted list for binary search lat/long Dim YList As New List ( Of Double ) Dim XList As New List ( Of Double ) 'Dictionary for fast assigning of coordinates to pixels Dim YDict As Dictionary ( Of Double, Integer ) = New Dictionary ( Of Double, Integer ) Dim XDict As Dictionary ( Of Double, Integer ) = New Dictionary ( Of Double, Integer ) Function bestPixel ( ByVal searchValueLat As Double, ByVal searchValuelng As Double ) As GMap. After doing some research, I believe this is one of the fastest ways to map millions of points in just a few seconds. It is a fast, geo-modified binary search that assigns the best pixel-location for each pair of coordinates.

#Xlist location code#

The following code is at the heart of the Lat/Lng-point mapping. So far, data can be structured spatially using QuadTrees (each subfolder represents a single quad) or temporally based on Days, Months or Years (etc.)

Data is pre-structured to improve clipping and filtering.

Instead, each line is copied as a whole from original to output CSV

When exporting/clipping data, CSVs are not re-formatted.

CSV files are not read fully, column by column, but line by line, using Streamreader, and only up to the point in each line where data is required.

How the speed of reading data and exporting CSV data is improved in ClipGeo: Such as ArcGIS, for more advanced analysis. This tool was build to initially extract parts of a larger point dataset to be imported into other Software, My experience was that beyond 5 million points, ArcGIS quits.

The tool is optimized for speed.įor example, by using a geo-modified binary search, it is possible to map and extract 6 million photo locations in Germany in under 2 Minutes on a regular laptop.įiltering, extracting, clipping and visualizing large georeferenced point datasets is not possible with common GIS Software, such as ESRI ArcGIS. Large georeferenced point datasets (such as 200 Million Flickr photo locations). Large Spatial Point Dataset Extraction and VisualizationĬlipGeo is a side project I developed over the years to clip, extract and visualize simple but very