WorldView - Revision history

Neteler: updated from DigitalGlobe documentation

2020-04-08T13:27:41Z

updated from DigitalGlobe documentation

← Older revision		Revision as of 13:27, 8 April 2020
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	==== Spectral Radiance ====		==== Spectral Radiance ====

	Converting a Blue Band (Digital Numbers) in to Spectral at-sensor Radiance in the ''correct'' units to be further used for the conversion in to unitless Reflectance:		Converting a Blue Band (Digital Numbers) in to Spectral at-sensor Radiance in the ''correct'' units to be further used for the conversion in to unitless Reflectance.

			Citing from "Absolute Radiometric Calibration, Prepared By: Michele A. Kuester"
			https://dg-cms-uploads-production.s3.amazonaws.com/uploads/document/file/209/ABSRADCAL_FLEET_2016v0_Rel20170606.pdf

			''"The top-of-atmosphere radiance, L, in units of Wμm-1m-2sr-1, is then found from the DigitalGlobe image product for each band by converting from digital numbers
			(DN) using the equation,
			''
			L = Gain * DN * (abscalfactor/effective bandwidth) + Offset

			''The TDI specific "abscalfactor" and "effectiveBandwidth" are delivered with the imagery in the metadata file. The digital number, DN, is the pixel value found in the imagery. The Gain and Offset are the absolute radiometric calibration band dependent adjustment factors that are given in Table 1. Note that these are not necessarily stagnant values and they are revisited annually.
			"''

			(the "Table 1" is found in the same PDF file above. You may want to check if a newer table version exists).

	<source lang="bash">		<source lang="bash">
	# set the region		# set the region
	g.region rast=Blue_DNs -p		g.region rast=Blue_DNs -p

			# ?? convert DNs to spectral Radiance values
			# r.mapcalc "Blue_TOA_Radiance = ( (10000 * WorldView_Blue_DNs) / (... * ...) )"

	# convert DNs to spectral Radiance values		# convert DNs to spectral Radiance values
	r.mapcalc "~~Blue_Radiance~~ = ( ~~(10000 * WorldView_Blue_DNs)~~ / ~~(... * ...)~~ )"		r.mapcalc "Blue_TOA_Radiance = Gain * DN * (abscalfactor/effective bandwidth) + Offset"

	</source>		</source>

Neteler: remove hardcoded version specific urls, use latest version

2018-12-04T10:07:05Z

remove hardcoded version specific urls, use latest version

← Older revision		Revision as of 10:07, 4 December 2018
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	* {{cmd\|r.mapcalc}}		* {{cmd\|r.mapcalc}}
	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.colors.enhance\|~~version=70~~}}		* {{cmd\|i.colors.enhance\|}}
	* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}		* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}

⚠️NikosA: updated list of grass related modules

2016-08-14T08:16:44Z

updated list of grass related modules

← Older revision		Revision as of 08:16, 14 August 2016
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	* {{cmd\|r.mapcalc}}		* {{cmd\|r.mapcalc}}
	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.~~landsat~~.~~rgb~~}}		* {{cmd\|i.colors.enhance\|version=70}}
	* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}		* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}

⚠️NikosA: /* Pan-Sharpening */

2016-08-14T05:11:28Z

Pan-Sharpening

← Older revision		Revision as of 05:11, 14 August 2016
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	[http://en.wikipedia.org/wiki/Pansharpened_image Pan-Sharpening] / [http://en.wikipedia.org/wiki/Image_fusion Fusion] is the process of merging high-resolution panchromatic and lower resolution multi-spectral imagery. [http://grass.osgeo.org/grass70/ GRASS 7] holds a dedicated pan-sharpening module, {{cmd\|i.pansharpen}} which features three techniques for sharpening, namely the [http://wiki.awf.forst.uni-goettingen.de/wiki/index.php/Brovey_Transformation Brovey transformation], the classical IHS method and one that is based on [[Principal Components Analysis]] (PCA).		[http://en.wikipedia.org/wiki/Pansharpened_image Pan-Sharpening] / [http://en.wikipedia.org/wiki/Image_fusion Fusion] is the process of merging high-resolution panchromatic and lower resolution multi-spectral imagery. [http://grass.osgeo.org/grass70/ GRASS 7] holds a dedicated pan-sharpening module, {{cmd\|i.pansharpen}} which features three techniques for sharpening, namely the [http://wiki.awf.forst.uni-goettingen.de/wiki/index.php/Brovey_Transformation Brovey transformation], the classical IHS method and one that is based on [[Principal Components Analysis]] (PCA).
	Another algorithm deriving excellent detail and a realistic representation of original multispectral scene colors, is the High-Pass Filter Addition (HPFA) technique. It is implemented via the {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}} add-on (for GRASS 6, please refer to a bash shell script https://github.com/NikosAlexandris/i.fusion.hpf.sh which is, however, unmaintained).		Another algorithm deriving excellent detail and a realistic representation of original multispectral scene colors, is the High-Pass Filter Addition (HPFA) technique. It is implemented via the {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}} add-on (for GRASS 6, please refer to a bash shell script https://github.com/NikosAlexandris/i.fusion.hpf.sh which is, however, unmaintained).


	One approach inside GRASS-GIS to get an acceptable color-balanced composite image after Pan-sharpening 11-bit IKONOS spectral bands comprises the following steps		One approach inside GRASS-GIS to get an acceptable color-balanced composite image after Pan-sharpening 11-bit IKONOS spectral bands comprises the following steps

⚠️NikosA: added link to https://github.com/NikosAlexandris/i.worldview.toar

2016-08-14T05:10:22Z

added link to https://github.com/NikosAlexandris/i.worldview.toar

← Older revision		Revision as of 05:10, 14 August 2016
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	=== Deriving Physical Quantities ===		=== Deriving Physical Quantities ===

			Conversions implemented in the GRASS module [https://github.com/NikosAlexandris/i.worldview.toar i.worldview.toar]


	''ToCleanUp''		''ToCleanUp''

⚠️NikosA: /* Inside GRASS GIS */

2016-08-14T05:08:29Z

Inside GRASS GIS

← Older revision		Revision as of 05:08, 14 August 2016
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	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.landsat.rgb}}		* {{cmd\|i.landsat.rgb}}
			* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}
			* [https://github.com/NikosAlexandris/i.worldview.toar i.worldview.toar]
	* {{cmd\|i.vi}}		* {{cmd\|i.vi}}
	* {{cmd\|i.segment}}		* {{cmd\|i.segment}}

⚠️NikosA: added i.fusion.hpf

2016-08-14T05:07:32Z

added i.fusion.hpf

← Older revision		Revision as of 05:07, 14 August 2016
Line 299:		Line 299:

	[http://en.wikipedia.org/wiki/Pansharpened_image Pan-Sharpening] / [http://en.wikipedia.org/wiki/Image_fusion Fusion] is the process of merging high-resolution panchromatic and lower resolution multi-spectral imagery. [http://grass.osgeo.org/grass70/ GRASS 7] holds a dedicated pan-sharpening module, {{cmd\|i.pansharpen}} which features three techniques for sharpening, namely the [http://wiki.awf.forst.uni-goettingen.de/wiki/index.php/Brovey_Transformation Brovey transformation], the classical IHS method and one that is based on [[Principal Components Analysis]] (PCA).		[http://en.wikipedia.org/wiki/Pansharpened_image Pan-Sharpening] / [http://en.wikipedia.org/wiki/Image_fusion Fusion] is the process of merging high-resolution panchromatic and lower resolution multi-spectral imagery. [http://grass.osgeo.org/grass70/ GRASS 7] holds a dedicated pan-sharpening module, {{cmd\|i.pansharpen}} which features three techniques for sharpening, namely the [http://wiki.awf.forst.uni-goettingen.de/wiki/index.php/Brovey_Transformation Brovey transformation], the classical IHS method and one that is based on [[Principal Components Analysis]] (PCA).
			Another algorithm deriving excellent detail and a realistic representation of original multispectral scene colors, is the High-Pass Filter Addition (HPFA) technique. It is implemented via the {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}} add-on (for GRASS 6, please refer to a bash shell script https://github.com/NikosAlexandris/i.fusion.hpf.sh which is, however, unmaintained).

	One approach inside GRASS-GIS to get an acceptable color-balanced composite image after Pan-sharpening 11-bit IKONOS spectral bands comprises the following steps		One approach inside GRASS-GIS to get an acceptable color-balanced composite image after Pan-sharpening 11-bit IKONOS spectral bands comprises the following steps

⚠️NikosA: s/addon/cmd for i.pansharpen

2015-05-08T17:19:13Z

s/addon/cmd for i.pansharpen

← Older revision		Revision as of 17:19, 8 May 2015
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	==== Automatising Sharpening & RGB Composition ====		==== Automatising Sharpening & RGB Composition ====

	An ''experimental'' bash script to automatise the sharpening/fusion and RGB composition process is demonstrated here. The script uses the Spectral Reflectance values (double precision values), gained from previous steps (see above), and produces Pan-sharpened images by applying all of the three methods that {{~~addon~~\|i.pansharpen}} offers. In addition, it attempts to produce True-Color composite images, without and with re-balancing the color tables by using the {{cmd\|i.landsat.rgb}} module.		An ''experimental'' bash script to automatise the sharpening/fusion and RGB composition process is demonstrated here. The script uses the Spectral Reflectance values (double precision values), gained from previous steps (see above), and produces Pan-sharpened images by applying all of the three methods that {{cmd\|i.pansharpen}} offers. In addition, it attempts to produce True-Color composite images, without and with re-balancing the color tables by using the {{cmd\|i.landsat.rgb}} module.

⚠️NikosA: added link to python script i.worldview.toar

2015-05-08T17:15:11Z

added link to python script i.worldview.toar

← Older revision		Revision as of 17:15, 8 May 2015
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	==== Automatising Conversions ====		==== Automatising Conversions ====

	The conversion process can be scripted to avoid repeating the same steps for each band separately. ~~In bash, such a script might be as the following example. '''Note,''' however, in this example script constants, band parameters and acquisition related metadata are hard-coded!~~		The conversion process can be scripted to avoid repeating the same steps for each band separately.

			===== Python =====

			A custom python script, performing the operations of interest, might be like [https://github.com/NikosAlexandris/i.worldview.toar i.worldview.toar (for GRASS 7.x)]

			===== Bash =====
			In bash, such a script might be as the following example. '''Note,''' however, in this example script constants, band parameters and acquisition related metadata are hard-coded!

	<source lang="bash">		<source lang="bash">

⚠️Madi at 13:13, 24 September 2014

2014-09-24T13:13:49Z

← Older revision		Revision as of 13:13, 24 September 2014
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	Converting Digital Numbers to Radiance/Reflectance requires knowledge about the sensor's specific spectral band parameters. In the following listed ~~paramters~~ (see below), the ''Effective Bandwidth''s and the ''Band-Averaged Solar Spectral Irradiance''s are extracted from the document [http://www.digitalglobe.com/downloads/Radiometric_Use_of_WorldView-2_Imagery.pdf Radiometric Use of WorldView-2 Imagery, Technical Note (2010)] by Todd Updike and Chris Comp. The Absolute Calibration Factors are extracted from a WorldView-2 product, specifically from an image metadata file (extension .IMD).		Converting Digital Numbers to Radiance/Reflectance requires knowledge about the sensor's specific spectral band parameters. In the following listed parameters (see below), the ''Effective Bandwidth''s and the ''Band-Averaged Solar Spectral Irradiance''s are extracted from the document [http://www.digitalglobe.com/downloads/Radiometric_Use_of_WorldView-2_Imagery.pdf Radiometric Use of WorldView-2 Imagery, Technical Note (2010)] by Todd Updike and Chris Comp. The Absolute Calibration Factors are extracted from a WorldView-2 product, specifically from an image metadata file (extension .IMD).


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	The absolute radiometric calibration factor is dependent on the specific band,		The absolute radiometric calibration factor is dependent on the specific band,
	as well as the TDI exposure level, line rate, pixel ~~aggregration~~, and bit depth		as well as the TDI exposure level, line rate, pixel aggregation, and bit depth
	of the product. Based on these parameters, the appropriate value is provided in		of the product. Based on these parameters, the appropriate value is provided in
	the .IMD file. For this reason, care should be taken not to mix absolute radiometric		the .IMD file. For this reason, care should be taken not to mix absolute radiometric

← Older revision		Revision as of 10:07, 4 December 2018
Line 35:		Line 35:
	* {{cmd\|r.mapcalc}}		* {{cmd\|r.mapcalc}}
	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.colors.enhance\|~~version=70~~}}		* {{cmd\|i.colors.enhance\|}}
	* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}		* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}

← Older revision		Revision as of 08:16, 14 August 2016
Line 35:		Line 35:
	* {{cmd\|r.mapcalc}}		* {{cmd\|r.mapcalc}}
	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.~~landsat~~.~~rgb~~}}		* {{cmd\|i.colors.enhance\|version=70}}
	* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}		* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}

← Older revision		Revision as of 05:08, 14 August 2016
Line 36:		Line 36:
	* {{cmd\|r.colors}}		* {{cmd\|r.colors}}
	* {{cmd\|i.landsat.rgb}}		* {{cmd\|i.landsat.rgb}}
			* {{AddonSrc\|imagery\|i.fusion.hpf\|version=7}}
	* {{cmd\|i.pansharpen}}		* {{cmd\|i.pansharpen}}
			* [https://github.com/NikosAlexandris/i.worldview.toar i.worldview.toar]
	* {{cmd\|i.vi}}		* {{cmd\|i.vi}}
	* {{cmd\|i.segment}}		* {{cmd\|i.segment}}