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Processing Services

This section of the user manual aims to describe the processing services available in the ESA Charter Mapper. Each of the services are described one by one with the provision of all essential information for their correct usage and related examples. This introduction aims to provide all the necessary information required to better understand product specifications and tutorials of the multiple services.

List of processing services

In Table 1 is given the list of the EO data pre-processing services currently available in the ESA Charter Mapper. All the services are mapped in the table below with service number, service name and short name. The summary given in Table 1 also includes how these services are employed in the ESA Charter Mapper according to the type of disaster and production mode.

# Service name Short name Flood large Flash flood Tsunami S & H rural S & H urban Earthquake Landslide Wildfire Volcano
1 Optical Products Calibration OPT-Calib S S S S S S S S S
2 Optical Pan sharpened Image Generation PAN-Sharp OD OD OD OD OD OD OD OD OD
3 Radar Products Calibration SAR-Calib S S S S S S S S S
4 Multi-Sensor Band Composite COMBI S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD
5 Advanced Multi-Sensor Band Composite COMBI-Plus S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD
6 Optical Spectral Index Generation OPT-Index S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD S and OD
8 Co-located Stacking STACK OD OD OD OD OD OD OD OD OD
11 SAR Amplitude Change SAR-Change OD OD OD OD OD OD OD OD OD
15 Hotspot Detection HOTSPOT S and OD OD
17 Burned Areas Severity Analysis BAS OD

Table 1 - Outlook of the ESA Charter Mapper processing services and their application to specific disaster types. 'S' stands for Sytematic and 'OD' for On-Demand production modes

Different types of output products

In the ESA Charter Mapper two main types of Product can be derived from both systematic and on-demand processing services:

  1. Visual Products (Overview images as grayscale or RGB composite).
  2. Physical meaning Products (TOA reflectance, Brightness Temperature, sigma0 in dB, spectral index, PCs, interferometric coherence, LOS displacement, flood bitmask, hotspot bitmask).

Each of them is given by following a dedicated data structure (e.g. unit, data type, scale factor, valid range) with respect to the nature of the product, as described in Table 2.

Product Type EO data Description Unit Data type Scale factor Valid Range From service #
Overview Visual OPT, SAR Overview image as RGBA band composite or grayscale product Uint

8

[0, 255] all
Reflectance Physical OPT TOA reflectance for VIS, RE and SWIR CBNs (e.g. blue, nir) Uint

16

0.0001 [0, 10000] 1
Brightness temperature Physical OPT TOA brightness temperature for LWIR CBNs (e.g lwir11) K Uint

16

0.01 1
Spectral index Physical OPT Spectral index (NDVI, NDMIR, NBR, NDWI, NDWI2, MNDWI, NDBI) as normalized difference of CBNs in TOA reflectance. Float 32 [-1,1] 6, 17
Sigma nought Physical SAR Sigma nought for L-, C-, X-band SAR data in each polarization (e.g. sigma0-HH-db) dB Float 32 3, 11
Hotspot bitmask Physical OPT Hotspot bitmask from hotspot detection based on nir and swir22. (bitmask defined as 0=no-hotspot, 1=hotspot) 1-bit [0,1] 15
dNBR Physical OPT Difference between the pre and post Normalized Burn Ratio Uint

16

0.0001 [0, 10000] 17
RBR Physical OPT Relativized Burn Ratio using the pre and post Normalized Burn Ratio Uint

16

0.001 [0, 10000] 17
STACK OPT, SAR A stack of N-images including the reference and all secondary datasets produced by the co-location processor Float 32 8

Table 2 - Description, unit, bit-depth, scaling factor, valid range and originated service for all ESA Charter Mapper product types.

More details about each of the physical meaning or visual products of the ESA Charter Mapper can be found in the service description and product specification of each service (see service number in the last column of Table 1) which are reported in the section dedicated to processing services.

Visual products from optical EO data

Concerning the visual products, the term “overview” for visual products is adopted in the ESA Charter Mapper to be compliant with the pre-defined asset role types defined in the STAC standards1.

Pre-defined RGB band composites

Multiple pre-defined RGB band composites are available in the ESA Charter Mapper for optical EO data. All the possible RGB composite options are listed in Table 3 which also includes examples of the ones derivable from Landsat-7, Landsat-8 and Sentinel-2 missions with the associated CBN combination.

Code Composite RGB (CBN) Landsat-7

ETM+

Landsat-8

OLI

Sentinel-2

MSI

TRC True Color red, green, blue 3 2 1 4 3 2 4 3 2
CIV Color Infrared (vegetation) nir, red, green 4 3 2 5 4 3 8 4 3
LAW Land/Water nir, swir16, red 4 5 3 5 6 4 8A 11 4
VEA Vegetation Analysis swir16, nir, red 5 4 3 6 5 4 11 8A 4
SIR Shortwave Infrared swir22, nir, red 7 4 3 7 5 4 12 8A 4
FCU False Color Urban swir22, swir16, red 7 5 3 7 6 4 12 11 4
ATP Atmospheric Penetration swir22, swir16, nir 7 5 4 7 6 5 12 11 8A
WAD Water Depth green, blue, coastal - 3 2 1 3 2 1

Table 3 - RGB Composites for ESA Charter Mapper using CBN and their application for Landsat-8 and Sentinel-2 bands.

Color operations in the ESA Charter Mapper

In the ESA Charter Mapper a universal color formula is employed in the creation of all overviews of optical payload:

Gamma RGB 1.5 Sigmoidal RGB 10 0.3 Saturation 1

This formula is tailored for a general usage in the Processing Environment and employs different values than the rio-color2 default ones. In the ESA Charter Mapper the structure of a color formula is described in this section about the TiTiler4 tool of the ESA Charter Mapper Geobrowser.

The ESA Charter Mapper universal color formula can be used also to reproduce intra-sensor RGB on the fly in the TiTiler widget in the ESA Charter Mapper Layer Details tab under Layer Styling > Combine Assets > Color Formula.

The application of the universal color formula in the ESA Charter Mapper has shown a fairly good performance in the visualization of multiple RGB composites for most of the missions of the Optical payload. However the assumption of using a single color formula for multiple different sensors has an intrinsic limitation, as encountered in some missions (e.g. Kompsat-3A AEISS-A and ResourceSat-2/2A LISS-III). Therefore, a slightly modified version of the universal color formula has been proposed when necessary. Refined color formulas are included in Table 3.

Mission Sensor Modified color formula Valid for RGB
Kompsat-3A AEISS-A Gamma RGB 1.5 Saturation 1.1 Sigmoidal RGB 15 0.33 TRC, CIV
Gaofen-2 AEISS Gamma RGB 1 Saturation 1 Sigmoidal RGB 3 0.5 TRC, CIV
VRSS-2 PMC Gamma RGB 1.5 Saturation 1 Sigmoidal RGB 10 0.25 TRC, CIV
ALSAT-1B SLIM6 Gamma RGB 1.5 Saturation 1 Sigmoidal RGB 10 0.2 CIV
ResourceSat-2A LISS-III Gamma RGB 1.5 Saturation 2 Sigmoidal RG 5 0.3 Sigmoidal B 10 0.3 CIV
Gamma RGB 1.5 Saturation 1 Sigmoidal RG 5 0.5 Sigmoidal B 10 0.4 VEA

Table 3 - Modified versions of the universal color formula for multiple missions of the ESA Charter Mapper optical payload.

An example of a VEA RGB band composite obtained by using the modified color formula with the ResourceSata-2A LISS-III data is shown in Figure 1.

figure 1

Figure 1 - VEA RGB band composite of ResourceSat-2A data using the modified universal color formula (Image credit: ISRO).

Tailored RGB composites can be also made under Combine Assets using the Horizontal cumulative count cut 2-98% or by manually setting min/max for each RGB channel.

Visual products from SAR EO data

Overviews are also produced in the ESA Charter Mapper for the radar sensors. For single-pol SAR data such as the case of ICEYE products, the ESA Charter Mapper generates only one gray-scale overview product at full resolution in VV polarization. Instead, for dual- and ful- pol SAR data, the platform not only generates multiple grayscale overviews for each single polarization but also a RGB band composite from a combination of them.

Grayscale overviews are generated for each polarization available from the source SAR data (see Figure 2).

figure 2

Figure 2 - Gray-scale overview of TerraSAR-X EEC data in HH polarization over Palu (Image credit: DLR).

In the case of dual-pol data, VV&VH or HH&HV, the RGB is created with R=co-pol, G=cross-pol, and B=co-pol/cross-pol. This first representation highlights mainly urban areas, the different orientation of buildings, and vegetation.

figure 3

Figure 3 - Dual Pol Ratio RGB composite "overview-dual" from ALOS-2 PALSAR-2 data in HH/HV polarizations over Palu (Image credit: JAXA).

In case of full-poll data in the ESA Charter Mapper the RGB band composite is derived as follows: R=HH, G=HV, B=VV. This second representation improves the dual-pol representation, highlighting better volumetric scattering, bare soils and urban areas.

figure 4

Figure 4 - Full Pol RGB composite "overview-full" from SAOCOM-1A GTC full-pol data over the Russian Federation (Image credit: CONAE).

Valid ranges for different SAR polarization and bands

In the creation of all SAR visual products an image stretching is applied to consider only Sigma nought within predefined minimum and maximum values expressed in dB. Such valid ranges depend on SAR band and polarization and are listed in Table 4.

Polarization L C X
VV [-27,0] [-20,0] [-22,2]
HH [-27,0] [-20,0] [-22,2]
VH [-35,-5] [-26,-5] [-27,-3]
HV [-35,-5] [-26,-5] [-27,-3]

Table 4 - Valid ranges used for stretching Sigma Nought during the generation of SAR overviews products. The values in dB are given for multiple SAR-bands and polarizations.

Low resolution overview product

To deal with the restrictions imposed by the licensing policy of some Agencies for the access to full resolution data, the ESA Charter Mapper also generates overviews at low resolution. For each acquired product received from COS-2 notification, the ESA Charter Mapper generates a single overview product at low resolution using a pre-defined RGB band combination and/or grayscale downsampled image. The default low resolution overview for each mission of the ESA Charter Mapper payload is described in the below Table 5.

Mission Sensor Type Default low resolution overview product
ALOS-2 PALSAR-2 SAR overview-vv-low-res (or overview-hh-low-res)
ALSAT-1B SLIM-6 Optical overview-civ-low-res
CartoSat-2 PAN Optical overview-pan-low-res
CBERS-4 PAN/MUX Optical overview-trc-low-res
CBERS-4 WFI Optical overview-trc-low-res
CBERS-4A WPM Optical overview-trc-low-res
CBERS-4A PAN/MUX Optical overview-trc-low-res
CBERS-4A WFI Optical overview-trc-low-res
DEIMOS-1 SLIM-6 Optical overview-civ-low-res
DubaiSat-2 HiRAIS Optical overview-trc-low-res
Gaofen-1 PMS Optical overview-trc-low-res
Gaofen-1 WFV Optical overview-trc-low-res
Gaofen-2 PMS Optical overview-trc-low-res
Gaofen-3 SAR-C SAR overview-vv-low-res (or overview-hh-low-res)
Gaofen-4 PMS, IRS Optical overview-trc-low-res
GeoEye-1 EO imager Optical overview-trc-low-res
Kanopus-V 1/2/3 MSS/PSS Optical overview-trc-low-res
Kanopus-V-IK MSS/PSS Optical overview-trc-low-res
Kanopus-V-IK MSU-IK-SRM Optical overview-mwir38-low-res (or overview-lwir9-low-res)
KhalifaSat KHCS Optical overview-trc-low-res
KOMPSAT-2 MSC Optical overview-trc-low-res
KOMPSAT-3 AEISS Optical overview-trc-low-res
KOMPSAT-3A AEISS-A Optical overview-trc-low-res
KOMPSAT-5 COSI SAR overview-vv-low-res (or overview-hh-low-res)
ICEYE SAR-X SAR overview-vv-low-res
Landsat-7 ETM Optical overview-trc-low-res
Landsat-8 OLI Optical overview-trc-low-res
MeteorM KMSS MSU Optical overview-civ-low-res
PlanetScope PlanetScope Optical overview-trc-low-res
Pleiades PHR1A/B Optical overview-trc-low-res
RADARSAT-2 SAR-C SAR overview-vv-low-res (or overview-hh-low-res)
RCM SAR-C SAR overview-vv-low-res (or overview-hh-low-res)
ResourceSat-2 / 2A LISS-III Optical overview-civ-low-res
ResourceSat-2 / 2A LISS-IV Optical overview-civ-low-res
Resurs-P GEOTON-L1 Optical overview-trc-low-res
Resurs-P ShMSA-VR Optical overview-trc-low-res
SAOCOM-1A SAR-L SAR overview-vv-low-res (or overview-hh-low-res)
Sentinel-1 SAR-C SAR overview-vv-low-res (or overview-hh-low-res)
Sentinel-2 MSI Optical overview-trc-low-res
SPOT-6 SPOT-6 Optical overview-trc-low-res
SPOT-7 SPOT-7 Optical overview-trc-low-res
TerraSAR-X, TanDEM-X SAR-X SAR overview-vv-low-res (or overview-hh-low-res)
UK-DMC-2 SLIM-6 Optical overview-civ-low-res
Vision-1 VHRI-100 Optical overview-trc-low-res
VRSS-1 PMC Optical overview-trc-low-res
VRSS-1 WMC Optical overview-trc-low-res
VRSS-2 HRC Optical overview-trc-low-res
World-view1 WV60 Optical overview-pan-low-res
World-view2 WV110 Optical overview-trc-low-res
World-view3 WV110 Optical overview-trc-low-res

Table 5 - Definition of default low resolution overviews for each of the missions of the ESA Charter Mapper payload.

A common format for output raster products

All the output raster products derived from the ESA Charter Mapper Processing Service, which are summarized in Table 2, are given in the Cloud Optimized GeoTIFF (COG)3 format.

COG is an extension of the GeoTIFF format dedicated for data hosting on HTTP file servers. One of the main advantages in using COG format in cloud processing environments is that the single GeoTIFF file can be accessed by multiple clients with no need to copy or cache the desired product.

Furthermore, it allows the client to easily retrieve via HTTP GET range requests just a desired portion of the data required for more efficient workflows on the cloud. As an example, in the ESA Charter Mapper the pre-processed datasets are stored in COG format to reduce data transfer during the thematic processing. The COG format is already employed under multiple initiatives such as: OpenAerialMap, INPE, MAXAR/DigitalGlobe, Planet, NASA and Copernicus’s Mundi DIAS.

STAC and COG have been recently adopted by USGS for the provision of Landsat-7 and Landsat-8 products, as described in the USGS Data Format Control Book5 which describes the format of the data to be used in Collection 2 processing.


  1. SpatioTemporal Asset Catalog Core Specification, The core components of STAC, https://stacspec.org/core.html

  2. Rio-color rasterio plugin, GitHub repository

  3. Cloud Optimized GeoTIFF, An imagery format for cloud-native geospatial processing, [https://www.cogeo.org]](https://www.cogeo.org/){:target="_blank"}. 

  4. Dynamic tiling with TiTiler

  5. Landsat Cloud Optimized GeoTIFF Data Format Control Book, The core components of STAC, available at