Ortho image configuration¶
Ortho image resolution and format can be configured. Configuration options are common to all oty orthorectification sub-commands and default to sensible values when not supplied.
Resolution, data type and compression¶
Ortho resolution defaults to an estimate of the ground sampling distance. This can be changed with --res. The ortho data type defaults to the source image data type, and can be changed with --dtype.
Compression can be configured with --compress as either deflate or lzw (with any ortho data type), or jpeg (with the uint8 or uint16 ortho data types). If --compress is not specified, compression defaults to jpeg when the ortho data type is uint8, and to deflate otherwise. When jpeg compression is used with the uint16 data type, the ortho is 12 bit jpeg compressed.
Note
Support for 12 bit JPEG compression is Rasterio build / package dependent.
The next example orthorectifies using EXIF / XMP tags, and configures the ortho image with a 0.2m resolution, the uint8 data type, and deflate compression:
oty exif --dem odm/odm_dem/dsm.tif --res 0.2 --dtype uint8 --compress deflate odm/images/100_0005_0140.tif
Masking and overviews¶
Valid ortho pixels are masked with either an internal mask band or a nodata value. By default, an internal mask is used when the ortho image is jpeg compressed. This avoids jpeg artefacts in invalid areas. When the ortho is deflate or lzw compressed, the default is use to a nodata value based on the data type. Masking behaviour can be changed with --write-mask to write an internal mask, or --no-write-mask to use a nodata value.
Internal overviews are added by default. This can be changed with --no-build-ovw. In this example, we create an ortho image with deflate compression, internal masks, and no internal overviews:
oty exif --dem odm/odm_dem/dsm.tif --compress deflate --write-mask --no-build-ovw odm/images/100_0005_0140.tif
Custom creation options and driver¶
For ortho image configurations not possible with the above options, custom creation options can be specified with --creation-option. The --compress option is ignored, and no other creation options are set by Orthority when this is supplied.
The ortho can be formatted as a gtiff (GeoTIFF - the default) or cog (Cloud Optimised GeoTIFF) with --driver.
This example formats the ortho as a GeoTIFF with internal masks, and specifies custom creation options for tiled YCbCr JPEG compression with a quality of 90:
oty exif --dem odm/odm_dem/dsm.tif --write-mask --driver gtiff --creation-option tiled=yes --creation-option compress=jpeg --creation-option photometric=ycbcr --creation-option jpeg_quality=90 odm/images/100_0005_0140.tif