DataSet.GetNormalizedFloatValueAt Methods
Gets the raster value from a cell at the specified position, normalized by Scale and Offset.
Overload List
| Name | Description | |
|---|---|---|
| Public method | GetNormalizedFloatValueAt(Point point) | Gets the raster value from a cell at the specified position, normalized by Scale and Offset, using bilinear interpolation if the dataset is continuous. |
| Public method | GetNormalizedFloatValueAt(Point point, RasterFilter rasterFilter) | Gets the raster value from a cell at the specified position, normalized by Scale and Offset, using a given interpolation method. |
GetNormalizedFloatValueAt(Point point)
Gets the raster value from a cell at the specified position, normalized by Scale and Offset, using bilinear interpolation if the dataset is continuous.Syntax
public System.Single GetNormalizedFloatValueAt (
Point point
)Parameters
The position, expressed in the coordinate reference system of the dataset, to get a value at.
Return Value
c * Scale + Offset, if c is the stored value at the specified coordinate, and Scale and Offset are metadata.
Remarks
This method is similar to the GetFloatValueAt method, but it assumes that the dataset can read the metadata Scale and Offset, and if the raster cell value is c (and does not represent undefined), it will return
c * Scale + Offset
Motivation: it is sometimes convenient to represent continuous raster data as 16-bit integers, with a suitable Offset and Scale, since this will require less space than 32-bit floats. If the dataset can read Offset and Scale from metadata, then they will be added as double attributes on the raster features from the dataset. In most cases, Carmenta Engine does not use these attributes internally, so whether they are used is up to the application. However, this method (and GetNormalizedFloatValuesAt) will multiply the cell value by Scale and then add Offset, to give the cell value in a normalized unit.
Currently, only the GdalDataSet can read Offset and Scale from metadata. If the dataset cannot read Offset and Scale, this method will throw an exception, so you must instead call GetFloatValueAt and use the offset and scale in application code (if you know them).
Example
// Get the normalized float value at Gothenburg
public static float GetNormalizedFloatValueAtGothenburg(DataSet dataSet)
{
// The center coordinates of Gothenburg in Wgs8LongLat
Point gothenburgCenter = new Point(11.974560, 57.708870);
// Project the center coordinates of Gothenburg to the Crs of the DataSet
gothenburgCenter = dataSet.Crs.ProjectFromLongLat(gothenburgCenter);
// Get the normalized float value at Gothenburg center and return it.
// Currently, only the GdalDataSet can read Offset and Scale from meta data.
// If the dataset cannot read Offset and Scale, this method will throw an exception,
// so you must instead call GetFloatValueAt and use the Offset and Scale in
// application code (if you know them).
return dataSet.GetNormalizedFloatValueAt(gothenburgCenter);
}
GetNormalizedFloatValueAt(Point point, RasterFilter rasterFilter)
Gets the raster value from a cell at the specified position, normalized by Scale and Offset, using a given interpolation method.Syntax
public System.Single GetNormalizedFloatValueAt (
Point point,
RasterFilter rasterFilter
)Parameters
The position, expressed in the coordinate reference system of the dataset, to get a value at.
The interpolation method: either nearest-neighbor, bilinear or bicubic.
Return Value
c * Scale + Offset, if c is the stored value at the specified coordinate, and Scale and Offset are metadata.
Remarks
This method is similar to the GetFloatValueAt method, but it assumes that the dataset can read the metadata Scale and Offset, and if the raster cell value is c (and does not represent undefined), it will return
c * Scale + Offset
Motivation: it is sometimes convenient to represent continuous raster data as 16-bit integers, with a suitable Offset and Scale, since this will require less space than 32-bit floats. If the dataset can read Offset and Scale from metadata, then they will be added as double attributes on the raster features from the dataset. In most cases, Carmenta Engine does not use these attributes internally, so whether they are used is up to the application. However, this method (and GetNormalizedFloatValuesAt) will multiply the cell value by Scale and then add Offset, to give the cell value in a normalized unit.
Currently, only the GdalDataSet can read Offset and Scale from metadata. If the dataset cannot read Offset and Scale, this method will throw an exception, so you must instead call GetFloatValueAt and use the offset and scale in application code (if you know them).
Platforms
Windows, Linux, Android