Introduction

Raster Types

ArcGIS Raster Type provides a framework that allows consuming data using a unified data model within ArcGIS. A raster type identifies metadata information such as band wavelengths, processing templates and other relevant metadata information that can aide in performing advanced image analysis operations on the data.

Typically satellite data, such as Landsat, is delivered with a metadata file containing information such as sensor name, acquisition date, WRS path and row information etc. The metadata file also contains pointers to tif files, with each tif file containing data corresponding to the spectral wavelength of the data. A raster type enhances the experience of working with such data, by combining the different tif files into a single composite, thus representing the data as a Raster Product.

We can think of a raster type as a set of API functions that understand the format of the metadata structure associated with any data; and it can parse the metadata to retrieve information such as

• Paths to pixel data files
• Spatial reference information
• Metadata such as
  • Sensor name
  • Sun elevation, Sun azimuth, Sun distance
  • Acquisition date
  • Radiance/Reflectance parameters
• Processing templates - A raster type also defines the processing templates that are applicable to the type of data being read. The processing templates can combine different pieces of information from the source data to generate an output that is much more meaningful and convenient for further analysis. Most of the raster types based on sensor data define Multispectral as one of its processing templates. Many other templates can be defined based on the type of data available for a product. For example, Landsat 8 raster type defines various templates such as Multispectral, Panchromatic, Pansharpened, Vegetation, Cirrus, Snow/Ice etc.

ArcGIS comes with dozens of built-in raster types that allows users to work with various types of data.

• Files, tables, and web services raster types
• Satellite sensor raster types
• Aerial imagery raster types
• Multidimensional raster types

The Python Raster Types

Python raster type framework provides Python developers a simple API to implement custom raster types using the Python programming language. Python was chosen as the language for creating custom raster types because of its familiarity to the ArcGIS user community. Implementing custom raster types has its advantages. Even though ArcGIS supports a lot of out-of-the-box raster types, if the raster type you need doesn’t come with ArcGIS, you can develop one using this framework. We hope that, over time, this repository will grow and contain Python raster types for lot of various types of data.

Raster types implemented in Python can provide the same user experience as builtin raster types in ArcGIS. The framework supports the well-known Raster type properties and workflows when applying raster types in mosaic dataset operations - Add Rasters to Mosaic Dataset, for example.