Define Overviews (Data Management)

Summary

Defines the tiling schema and properties of the preprocessed raster datasets that will cover part or all of a mosaic dataset at varying resolutions.

Usage

Syntax

DefineOverviews_management (in_mosaic_dataset, {overview_image_folder}, {in_template_dataset}, {extent}, {pixel_size}, {number_of_levels}, {tile_rows}, {tile_cols}, {overview_factor}, {force_overview_tiles}, {resampling_method}, {compression_method}, {compression_quality})
ParameterExplanationData Type
in_mosaic_dataset

The path and name of the mosaic dataset.

Mosaic Layer
overview_image_folder
(Optional)

The folder or geodatabase where the overviews will be stored.

Overviews that are stored and managed within personal and file geodatabases have the default overview folder location in the same workspace as the residing geodatabase.

Workspace
in_template_dataset
(Optional)

A raster dataset or polygon feature class used to define the extent or shape of the overview.

The extent of the raster dataset will be used when using a raster dataset. The shape of the polygon will be used when using a feature class.

Raster Layer; Feature Layer
extent
(Optional)

Four coordinates defining the extent of the overview that will be generated.

This is specified as space delimited in the following order: X-minimum X-maximum Y-minimum Y-maximum.

The mosaic dataset boundary will be used to determine the extent of the overviews if an extent is not defined.

Extent
pixel_size
(Optional)

Base pixel size used to generate the overviews. The default is determined by the software.

Double
number_of_levels
(Optional)

The number of overview levels that will be generated.

For a number greater than 0, it will be the number of overview levels generated. For example, 3 will generate three levels of overviews. If the value is left blank or -1, then an optimal number of overviews will be generated by the system.

Long
tile_rows
(Optional)

Optimum number of rows in the overview.

The larger the value, the bigger the file, and the more likely it will need to be regenerated if any lower image changes.

This number can affect the number of overview images created. If it's a large number, then fewer overviews will be generated. If it's a small number, then more files are generated.

Long
tile_cols
(Optional)

Optimum number of columns in the overview.

The larger the value, the bigger the file, and the more likely it will need to be regenerated if any lower image changes.

This number can affect the number of overview images created. If it's a large number, then fewer overviews will be generated. If it's a small number, then more files are generated.

Long
overview_factor
(Optional)

The ratio used to determine the size of the next overview. For example, if the cell size of the first level is x, and the overview factor is 3, then the next overview pixel size will be 3x.

Long
force_overview_tiles
(Optional)

Affects the levels at which overviews will be generated.

  • NO_FORCE_OVERVIEW_TILESOverviews will only be created at levels above the primary raster pyramids levels. This is the default.
  • FORCE_OVERVIEW_TILES Overviews will be created at all levels, even though the primary rasters have pyramids.
Boolean
resampling_method
(Optional)

The resampling algorithm used when creating the overviews.

  • NEARESTNearest neighbor assignment.
  • BILINEARBilinear interpolation. This is the default.
  • CUBICCubic convolution.
String
compression_method
(Optional)

This defines the type of data compression that will be used to store the overview images.

  • JPEGA lossy compression. This is the default.
  • NoneNo data compression.
  • LZWA lossless compression.
String
compression_quality
(Optional)

Quality of the compression used with the JPEG compression method. The compression quality can range from 1 to 100. A higher number means better image quality but less compression.

Long

Code Sample

DefineOverviews example 1 (Python window)

This is a Python sample for DefineOverviews.

import arcpy
arcpy.DefineOverviews_management("c:/workspace/fgdb.gdb/md01", "c:/temp",
                                 "#", "#", "30", "6", "4000", "4000", "2",
                                 "CUBIC", "JPEG", "50")
DefineOverviews example 2 (stand-alone script)

This is a Python script sample for DefineOverviews.

##===========================
##Define Overviews
##Usage: DefineOverviews_management in_mosaic_dataset {overview_image_folder}
##                                  {in_template_dataset} {extent} {pixel_size}
##                                  {number_of_levels} {tile_rows} {tile_cols}
##                                  {overview_factor} {NO_FORCE_OVERVIEW_TILES
##                                  | FORCE_OVERVIEW_TILES} {BILINEAR | NEAREST
##                                  | CUBIC}, {JPEG | None | LZW} {compression_quality}

try:
    import arcpy
    arcpy.env.workspace = "C:/Workspace"
    # Define Overviews to the default location
    # Define Overviews for all levels - ignore the primary Raster pyramid
    # Define Overviews compression and resampling method
    arcpy.DefineOverviews_management("DefineOVR.gdb/md", "#", "#", "#", "#", "#",
                                     "#", "#", "#", "FORCE_OVERVIEW_TILES",
                                     "BILINEAR", "JPEG", "50")
                                  
    
    # Define Overviews to the same File Geodatabase
    # Define Overview starting cell size, number of levels, maximum size and factor 
    arcpy.DefineOverviews_management("DefineOVR.gdb/md", "DefineOVR.gdb", "#",
                                     "#", "3", "6", "4000", "4000", "2", "#",
                                     "CUBIC", "None", "#")
    
except:
    print "Define Overviews example failed."
    print arcpy.GetMessages()
    

Environments

Related Topics

Licensing Information

ArcView: No
ArcEditor: Yes
ArcInfo: Yes

10/27/2014