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Mpe Formulas

The document discusses a tool that extracts data from HDF files of Modis products. It utilizes libraries to project coordinates and extract data for specific points. It also allows defining a region and checks Modis cells within the region, assigning values outside the region as -99.

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AgriMetSoft
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39 views2 pages

Mpe Formulas

The document discusses a tool that extracts data from HDF files of Modis products. It utilizes libraries to project coordinates and extract data for specific points. It also allows defining a region and checks Modis cells within the region, assigning values outside the region as -99.

Uploaded by

AgriMetSoft
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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AgriMetSoft

Modis Product Extractor


Modis Product Extractor is a tool designed to extract data from HDF files of Modis

products. To projection the coordinates in this data extraction, the tool utilizes

the Unidata Java NetCDF library. Below are the codes used to extract data for a

specific point:

ucar.nc2.dt.grid.GridDataset gds =
ucar.nc2.dt.grid.GridDataset.open(fileName);

ucar.nc2.dt.GridDatatype grid =
gds.findGridDatatype(VariableName);

ucar.nc2.dt.GridCoordSystem gcs = grid.getCoordinateSystem();

var xy = gcs.findXYindexFromLatLon(lat,lon, null);

var dd = mainVar.read(new int[2] { xy[1], xy[0] }, new int[2] {


1, 1 });

In the second tab, you can define a region. During this process, the tool's

underlying code generates an enclosed rectangle for your specified region and

checks all the Modis cells within this rectangular area to determine whether they

are within your defined region or not. During extraction, all cells outside your

designated region will be assigned a value of -99, while cells within the region will

retain the values retrieved from the HDF file, which may include numeric values

or NaN, depending on your HDF files.

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When we need to verify which cell from the file falls within the user-defined
polygon, we employ the NetTopologySuite library in conjunction with the
following code:

data[i,j].IsInA =
NetTopologySuite.Algorithm.CGAlgorithms.IsPointInRing(new
GeoAPI.Geometries.Coordinate(it.Lon,it.Lat),
polygon.Shell.Coordinates);

To read a shapefile, we utilize the "Catfood.Shapefile" library, a .NET-based tool

designed for read-only enumeration of ESRI shapefiles. This library supports all 2D

shape types, including Point, MultiPoint, PolyLine, and Polygon, along with their

associated metadata.

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