Description of the SPOTMaps 1.5 product

Transcription

1 Reference: S-ST-CA8-06-ADSI Issue: 1 Revision: 0 Date: 18/12/2015 CM chronology: 6899 First issued: 18/12/2015 Intelligence Operations / Exploitation Department Description of the SPOTMaps 1.5 product Name and job Acronym Date Signature Author Nathalie DUPIN DE SAINT CYR 18/12/2015 TCIIL1 Approved by Alexis BAROT 18/12/2015 TCIIL Authorized for application by Jean-Bernard MAYBON 05/01/2016 TCIIT2 Technical Documentation Manager Viviane MARSAC 11/01/2016 TCIFE Airbus Defence and Space 5 rue des Satellites B.P F Toulouse Cedex 4 - FRANCE Phone: 33 (0) Fax: 33 (0)

2 Description of the SPOTMaps 1.5 product Page n i2 Distribution Copies to: Fabrice Triffaut Alexandra Lambert Xavier de Butler Alexis Barot Laurent Bascle Janos Tegzes Didier Giacobbo Jean-François Voidrot To the attention of Managers : for diffusion to your teams

3 Description of the SPOTMaps 1.5 product Page n i3 Changes and status paragraphs Issue Rev. Date Reason for change Modified or added paragraphs /12/2015 New document

4 Description of the SPOTMaps 1.5 product Page n i4 Airbus D&S produces SPOTMaps 1.5 orthomosaic products from Spot 6/7 imagery with a resolution of 1.5 m. SPOTMaps 1.5 products are produced from a complete coverage of Spot 6/7 images and are radiometrically harmonised* to offer the user seamless easy viewing of the covered territory. The figure below illustrates an example of the SPOTMaps 1.5 product. Figure 1: View of a SPOTMaps product Oman * For technical reasons of data volume size, production is done in large batches. This can entail small radiometric differences between batches. Otherwise, within the same batch, local differences due to seasonal deviations can occur.

5 Description of the SPOTMaps 1.5 product Page n i5 Table of contents 1 Introduction SPOTMaps 1.5 features Composition Structure Product format Data acquisition SPOTMaps 1.5 specifications Features of SPOTMaps 1.5 data Data format and coding Reference documents Spacing Production process Overview of the production process Spatial triangulation and ortho-rectification Mosaiking Radiometric finishing Supply performance Quality control Spatial triangulation phase Mosaiking phase Formatting phase Volume of the SPOTMaps 1.5 product... 6 APPENDIX 1 : SPOTMaps 1.5 coverage on 12 November APPENDIX 2: Reference3D DEM late

6 Description of the SPOTMaps 1.5 product Page n 1 1 Introduction The purpose of this document is to describe the specifications and format of SPOTMaps 1.5 products, exclusively produced from pan-sharpened Spot 6/7 images. By default, the SPOTMaps 1.5 product includes a raster layer and a KML file for product discovery providing a view in Google Earth. There are many applications, and SPOTMaps 1.5 products are used in geographic information systems (GIS) for a wide range of applications related to mapping and land management. Appendix 1 illustrates SPOTMaps 1.5 coverage on 12 November 2015

7 Description of the SPOTMaps 1.5 product Page n 2 2 SPOTMaps 1.5 features 2.1 Composition The SPOTMaps 1.5 ortho-mosaic product meets a high standard of quality by employing the following criteria: global consistency of the product's radiometric effect by adaptation of the contrast and colours to ultimately produce a uniform result, in the production batch (see 4.1), giving the impression of a single image, good planimetric precision, variable according to the calibration source used, cloudless product (or with minimum cloud cover) by using image stacking in cloudy areas and the astute placement of cutlines, presence of metadata (supply of cutlines, dates). 2.2 Structure The SPOTMaps 1.5 product is an orthomosaic, supplied to the km², framed according to the customer area. 2.3 Product format The SPOTMaps 1.5 product is supplied as standard in GeoTIFF format. It comes as a set of files: GeoTIFF files, 8 bits, 3 uncompressed RGB bands for the orthomosaic One KML file containing the graph of cutlines acquisition dates from the source images The product comes in the WGS84 geographic system or on request in a UTM cartographic projection (Universal Transverse Mercator) on WGS84. In the WGS84 geographic system, the tiles have fixed size of 15 x15 (equivalent to 30 km x 30 km at the equator). In UTM cartographic projections, the tiles have fixed size of 27 km x 27 km. 2.4 Data acquisition The road map for Spot 6/7 acquisition areas for constituting world coverage in SPOTMaps 1.5 produces satellite programming requests, assigned different priority levels. This road map is periodically revised to integrate new requests. The programming of SPOTMaps 1.5 productions features the following parameters: Shooting angle limited to 20 Global cloud coverage of the SPOTMaps 1.5 product*: o Less than or equal to 10% by default o Less than or equal to 5% on dense urban areas ** o Less than or equal to 20% in tropical areas * Depending on the location, the customer's area of interest may not comply locally with the specification of cloud coverage which is global ** A dense urban area is visually assessed on the image by an operator

8 Description of the SPOTMaps 1.5 product Page n 3 3 SPOTMaps 1.5 specifications 3.1 Features of SPOTMaps 1.5 data The features of the SPOTMaps orthomosaic product are summarised in the following table: SPOTMaps orthomosaic Source data Primary Spot 6/7, pan-sharpened 3 RGB bands Resolution 1.5 m Spectral mode Natural colours (3 bands, RGB), 256 levels, 8 bits per band Location accuracy 5 m to 15 m CE90 Pre-processing Ortho-rectification with MNS Ref3D Coordinate system Geographic on WGS84 or UTM / WGS84 projections Format GeoTIFF Metadata KML Tile size 15 x 15 in WGS84 30 km x 30 km in UTM / WGS84 Table 1: SPOTMaps product features The mosaic's radiometrics are globally optimised to produce a seamless effect at a batch level: consequently, a radiometric deviation can exist between two neighbouring batches. Otherwise, if significant variations are present in the source images (e.g. because of seasonal deviations) within a batch, priority is given to the compliance of the radiometric details of the source images over the global seamless effect of the mosaic. Radiometric homogenisation covers terrestrial surfaces: sea areas are not equalised. 3.2 Data format and coding The format of the SPOTMaps 1.5 raster product is an uncompressed GeoTIFF, with 24-bit encoding and 3 RGB channels (8 bit/channel). When no islands are present (visual assessment by an operator), the sea may not be covered (no data, value 0) Reference documents Optionally, SPOTMaps 1.5 comes with: geographic coordinates in the WGS84 geodesic system cartographic coordinates in a WGS84 UTM projection Spacing The post spacing of the SPOTMaps 1.5 product is: 1/20 second of arc for geographic products (corresponding to around 1.5 m at the equator) 1.5 m for cartographic products

9 Description of the SPOTMaps 1.5 product Page n 4 4 Production process 4.1 Overview of the production process For practical reasons, production is done in significant size batches of around 350,000 km². The various production steps of the orthomosaic are: spatial triangulation and ortho-rectification, mosaiking comprised of determining the cutlines between the images and radiometric equalisation, corresponding to linear adaptation of the radiometry of the images before assembly, radiometric finishing to attenuate possible radiometric defects related to the mosaiking process, formatting the product by framing according to a defined assembly table Spatial triangulation and ortho-rectification The products are mainly produced on the basis of Reference3D calibration. The DEM mainly used in the ortho-rectification phase is the Reference3D DEM (80 million km² available). Appendix 2 Besides, spatial triangulation will ensure planimetric precision less than 15 m CE Mosaiking The main steps of the mosaiking process (choice of cutline, radiometric equalisation) are performed in subresolution; in general, a factor 6 of data sub-spacing is used, corresponding to sub-resolution of 9 m. Subresolution generally ensures the quality of the cutlines and the generated colour, while enabling optimal progress of the automatic processing. A 12-bit mosaic in sub-resolution is then calculated from the mosaiking lines and the radiometric equalisation once validated; it is then converted to 8 bits with colour effect optimisation. The end product is the result at the end of the calculations in full resolution of the 8-bit mosaic using the previously validated 8-bit mosaic as radiometric reference Radiometric finishing The radiometric quality criterion of the product can require the local radiometric retouching of certain defects mainly related to the mosaiking phase. 4.2 Supply performance The production time of a new SPOTMaps 1.5 batch is around 8 weeks for an average surface area of 350,000 km². For larger areas, a feasibility study is required for giving a realistic production time.

10 Description of the SPOTMaps 1.5 product Page n 5 5 Quality control 5.1 Spatial triangulation phase The controls of this phase are based on: The image residue found on the connection points, The planimetric residue found on the ground control points, The planimetric deviations measured against the planimetric reference data used in the spatial triangulation (in general, the Reference3D ortho-image base) 5.2 Mosaiking phase The controls of this phase are based on: Validation of the graph of the cutlines between the images Validation of the global colour of the final product Visual inspection of the full resolution tiles 5.3 Formatting phase The controls of this phase are based on: Inspection of the format Inspection of the geo-referencing of the raster tiles Visualisation of the product view in Google Earth

11 Description of the SPOTMaps 1.5 product Page n 6 6 Volume of the SPOTMaps 1.5 product The volume of the SPOTMaps 1.5 product varies according to the area in question. For example, for a SPOTMaps 1.5 product in geographic system at post spacing 1/20 second of arc or in cartographic projection at post spacing 1.5 m: Example of ordered area 1 x1 12,000 km² (at the equator) 30 x30 3,000 km² (at the equator) 15 x km² (at the equator) Total volume 15.2 GB 3.8 GB 950 GB Number of tiles Table 2: indicative volumes of SPOTMaps 1.5 products in geographic system Example of ordered area 120 km x 120 km 14,400 km² 60 km x 60 km 3,600 km² 30 km x 30 km 900 km² Total volume 18.4 GB 4.6 GB 1150 MB Number of tiles Table 3: indicative volumes of SPOTMaps 1.5 products in cartographic projection The output SPOTMaps product is comprised of a set of compressed files (one.zip file per tile with volume of around 1 GB).

12 Format of Product Description of the SPOTMaps 1.5 product Page n AN1 APPENDIX 1 : SPOTMaps 1.5 coverage on 12 November 2015

13 Format of Product Description of the SPOTMaps 1.5 product Page n AN2 APPENDIX 2: Reference3D DEM late 2014

14 Format of Product Description of the SPOTMaps 1.5 product Page n AN3 END OF DOCUMENT