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| − | == 4.1 Region and projection ==
| + | __TOC__ |
| − | === 4.1.1 Region of Interest === | + | {{scientific}} |
| | + | == Region of Interest == |
| | Geographical framing of the products of the different sensors in MCYFS | | Geographical framing of the products of the different sensors in MCYFS |
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| | [[File:RegionOfInterest.png]] | | [[File:RegionOfInterest.png]] |
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| − | === 4.1.2 Projection === | + | == Projection == |
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| | All the MCYFS remote sensing data over the pan-European continent are stored in the INSPIRE-LAEA system, as prescribed by the EU INSPIRE initiative. The INSPIRE-LAEA system is defined as follows: | | All the MCYFS remote sensing data over the pan-European continent are stored in the INSPIRE-LAEA system, as prescribed by the EU INSPIRE initiative. The INSPIRE-LAEA system is defined as follows: |
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| | ** True origin at Lon<sub>0</sub> = 10.00°, Lat<sub>0</sub> = 52.00° | | ** True origin at Lon<sub>0</sub> = 10.00°, Lat<sub>0</sub> = 52.00° |
| | ** Map shift: false easting X<sub>0</sub> = 4 321 000 m, false northing Y0 = 3 210 000 m | | ** Map shift: false easting X<sub>0</sub> = 4 321 000 m, false northing Y0 = 3 210 000 m |
| − | * Image Framing: the northwestern corner is fixed (X<sub>min</sub>=2 275 000 m, | + | * Image Framing: the northwestern corner is fixed (X<sub>min</sub>=2 275 000 m, Y<sub>max</sub>=5 415 000 m) but the southeastern extension varies slightly with the resolution. |
| − | Y<sub>max</sub>=5 415 000 m) but the southeastern extension varies slightly with the resolution. | |
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| − | == 4.2 Formats ==
| + | [[Category:Remote Sensing]] |
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| − | Three types of deliverables are foreseen: ENVI raster images, QuickLook Maps and Databases of Regional Unmixed Means. The three formats are discussed below:
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| − | * Images
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| − | * Quicklooks
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| − | * Regional Unmixed Means
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| − | === 4.2.1 Images ===
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| − | ==== 4.2.1.1 Image data ====
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| − | The image data are stored in “flat 2D” binary files, without leader/trailer bytes, and with file name extension “.IMG”. The data type can be byte, short integer, long integer or floating point. In practice, all efforts are made to save disk space by storing the images as far as possible in the most compact Byte data type (1 byte per pixel). Only for DMP the Short Integer data type is used (2 bytes per pixel). “Flat 2D” means that every image “layer” (e.g. different bands of the same registration) is stored in a separate image file. This approach makes the imagery software-independent: this generic file type can be ingested by any (commercial) image processing package.
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| − | The ancillary information (spatial, spectral, temporal characteristics) is stored in small ASCII-files with the same name as the IMG, but with a different extension. These annotation files are software specific. By default, we generate for each IMG an associated HDR-file, compatible with the widely used package IDL-ENVI. Similar annotation files can be generated for other systems. A description of the enriched ENVI-HDR file is provided in Headers.
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| − | 3D multi-band images are not appropriate for the (mostly) huge images of MCYFS. As an alternative, “metafiles” are provided. These are small ASCII-files with the names of all the images which belong together for a certain application. A metafile can be “opened” as if it were a single 3D image file. Removal or addition of new layers only requires editing the metafiles, not the copying of huge image data amounts. Again, metafiles are software specific, and by default we generate “MTA-files” for ENVI and similar “VAR-files” for GLIMPSE.
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| − | | |
| − | ==== 4.2.1.2 Headers ====
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| − | All delivered imagery is directly compatible with IDL-ENVI. However, a number of non-ENVI items are added to the HDR-files. These provide additional and essential information which is not stored by ENVI (see table for an overview of the different HDR-items):
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| − | * Temporal: the registration date and the length of the compositing period.
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| − | * Spectral: At the level of the digital image values (V), clear distinction is made between the “significant range” (Vlo-Vhi) and all values beyond this range, which are treated as “flags” (codes to indicate special cases). To this goal, the HDR-files contain the following two additional items:
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| − | Values = { Yname, Yunit, Vlo, Vhi, Vmin, Vmax, Vint, Vslo }
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| − | * Yname/unit= Name/Unit of the represented physical variable Y.
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| − | Eg.: NDVI (-) or DMP (kgDM/ha/day).
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| − | * Vlo/hi = Significant range of digital values to be treated as representing this physical var.
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| − | * min/max= Observed extremes for the IMG at hand, with: Vlo ≤ Vmin ≤ Vmax ≤ Vhi.
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| − | * Vint/slo = Intercept/slope of linear relation between V and physical Y: Y = Vint + Vslo.V.
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| − | Flags = { Vf1=Vf1,txt, Vf2=Vf2,txt, …}
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| − | * Vfi = Flag digital number (beyond significant range Vlo-Vhi)
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| − | * Vfi, txt = Meaning of this flag (textual)
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| − | Below, this ENVI-format with “enriched HDR-info” is called the ENVI/GLIMPSE image format.
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| − | Contents of the ENVI/GLIMPSE HDR-Files. The keywords are grouped per category.
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| − | Non-standard keywords, added by GLIMPSE are marked in grey.
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Region of Interest
Geographical framing of the products of the different sensors in MCYFS
Dxy = pixel size/resolution (1°/112=0.00892857143)
Xmin … Ymax = Map co-ordinates of IMG-edges, which are the co-ordinates of the outer edges of these pixels.
Ncol, Nrec, Npix = number of columns, records and pixels
Projection
All the MCYFS remote sensing data over the pan-European continent are stored in the INSPIRE-LAEA system, as prescribed by the EU INSPIRE initiative. The INSPIRE-LAEA system is defined as follows:
- Geodetical datum: ETRS89
- Map Projection:
- Family: Lambert Azimuthal Equal Area (LAEA), with the formulae holding for the ellipse (Snyder, 1987).
- Projection ellipse: GRS80 (same as WGS84)
- True origin at Lon0 = 10.00°, Lat0 = 52.00°
- Map shift: false easting X0 = 4 321 000 m, false northing Y0 = 3 210 000 m
- Image Framing: the northwestern corner is fixed (Xmin=2 275 000 m, Ymax=5 415 000 m) but the southeastern extension varies slightly with the resolution.
