| 1 | RFC2: Well Known Binary format for RASTER type |
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| 2 | ---------------------------------------------- |
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| 3 | $Author$ |
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| 4 | $Date$ |
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| 5 | $Revision$ |
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| 6 | ------------------------------------------------------ |
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| 7 | |
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| 8 | The WKB format for RASTER is meant for transport. |
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| 9 | Takes into account endiannes and avoids any padding. |
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| 10 | Still, beside padding and endiannes, it matches the |
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| 11 | internal serialized format (see RFC1), for quick |
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| 12 | input/output. |
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| 13 | |
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| 14 | // Basic Type definitions |
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| 15 | // byte : 1 byte |
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| 16 | // uint16 : 16 bit unsigned integer (2 bytes) |
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| 17 | // uint32 : 32 bit unsigned integer (4 bytes) |
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| 18 | // float64 : double precision floating point number (8 bytes) |
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| 19 | |
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| 20 | +------------------------------------------------------------+ |
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| 21 | | RASTER | |
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| 22 | +---------------+-------------+------------------------------+ |
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| 23 | | - name - | - type - | - meaning - | |
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| 24 | +---------------+-------------+------------------------------+ |
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| 25 | | endiannes | byte | 1:ndr/little endian | |
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| 26 | | | | 0:xdr/big endian | |
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| 27 | +---------------+-------------+------------------------------+ |
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| 28 | | version | uint16 | format version (0 for this | |
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| 29 | | | | structure) | |
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| 30 | +---------------+-------------+------------------------------+ |
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| 31 | | nBands | uint16 | Number of bands | |
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| 32 | +---------------+-------------+------------------------------+ |
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| 33 | | scaleX | float64 | pixel width | |
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| 34 | | | | in geographical units | |
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| 35 | +---------------+-------------+------------------------------+ |
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| 36 | | scaleY | float64 | pixel height | |
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| 37 | | | | in geographical units | |
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| 38 | +---------------+-------------+------------------------------+ |
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| 39 | | ipX | float64 | X ordinate of upper-left | |
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| 40 | | | | pixel's upper-left corner | |
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| 41 | | | | in geographical units | |
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| 42 | +---------------+-------------+------------------------------+ |
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| 43 | | ipY | float64 | Y ordinate of upper-left | |
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| 44 | | | | pixel's upper-left corner | |
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| 45 | | | | in geographical units | |
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| 46 | +---------------+-------------+------------------------------+ |
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| 47 | | skewX | float64 | rotation about Y-axis | |
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| 48 | +---------------+-------------+------------------------------+ |
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| 49 | | skewY | float64 | rotation about X-axis | |
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| 50 | +---------------+-------------+------------------------------+ |
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| 51 | | srid | int32 | Spatial reference id | |
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| 52 | +---------------+-------------+------------------------------+ |
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| 53 | | width | uint16 | number of pixel columns | |
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| 54 | +---------------+-------------+------------------------------+ |
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| 55 | | height | uint16 | number of pixel rows | |
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| 56 | +---------------+-------------+------------------------------+ |
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| 57 | | bands[nBands] | RASTERBAND | Bands data | |
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| 58 | +---------------+-------------+------------------------------+ |
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| 59 | |
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| 60 | |
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| 61 | +------------------------------------------------------------------+ |
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| 62 | | RASTERBAND | |
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| 63 | +---------------+--------------+-----------------------------------+ |
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| 64 | | - name - | - type - | - meaning - | |
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| 65 | +---------------+--------------+-----------------------------------+ |
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| 66 | | isOffline | 1bit | If true, data is to be found | |
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| 67 | | | | on the filesystem, trought the | |
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| 68 | | | | path specified in RASTERDATA | |
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| 69 | +---------------+--------------+-----------------------------------+ |
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| 70 | | hasNodataValue| 1bit | If true, stored nodata value is | |
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| 71 | | | | a true nodata value. Otherwise | |
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| 72 | | | | the value stored as a nodata | |
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| 73 | | | | value should be ignored. | |
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| 74 | +---------------+--------------+-----------------------------------+ |
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| 75 | | reserved | 2bits | unused in this version | |
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| 76 | +---------------+--------------+-----------------------------------+ |
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| 77 | | pixtype | 4bits | 0: 1-bit boolean | |
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| 78 | | | | 1: 2-bit unsigned integer | |
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| 79 | | | | 2: 4-bit unsigned integer | |
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| 80 | | | | 3: 8-bit signed integer | |
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| 81 | | | | 4: 8-bit unsigned integer | |
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| 82 | | | | 5: 16-bit signed integer | |
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| 83 | | | | 6: 16-bit unsigned signed integer | |
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| 84 | | | | 7: 32-bit signed integer | |
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| 85 | | | | 8: 32-bit unsigned signed integer | |
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| 86 | | | | 9: 32-bit float | |
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| 87 | | | | 10: 64-bit float | |
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| 88 | +---------------+--------------+-----------------------------------+ |
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| 89 | | nodata | 1 to 8 bytes | Nodata value | |
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| 90 | | | depending on | | |
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| 91 | | | pixtype [1] | | |
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| 92 | +---------------+--------------+-----------------------------------+ |
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| 93 | | data | RASTERDATA | Raster band data (see below) | |
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| 94 | +---------------+--------------+-----------------------------------+ |
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| 95 | |
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| 96 | +------------------------------------------------------------------+ |
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| 97 | | RASTERDATA (isOffline flag clear) | |
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| 98 | +---------------+--------------+-----------------------------------+ |
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| 99 | | pix[w*h] | 1 to 8 bytes | Pixels values, row after row, | |
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| 100 | | | depending on | so pix[0] is upper-left, pix[w-1] | |
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| 101 | | | pixtype [1] | is upper-right. | |
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| 102 | | | | | |
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| 103 | | | | As for endiannes, it is specified | |
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| 104 | | | | at the start of WKB, and implicit | |
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| 105 | | | | up to 8bits (bit-order is most | |
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| 106 | | | | significant first) | |
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| 107 | | | | | |
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| 108 | +---------------+--------------+-----------------------------------+ |
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| 109 | |
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| 110 | [1] 1,2 and 4 bit pixtypes are still encoded as 1-byte per value |
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| 111 | |
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| 112 | +-----------------------------------------------------------------+ |
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| 113 | | RASTERDATA (isOffline flag set) | |
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| 114 | +---------------+-------------+-----------------------------------+ |
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| 115 | | bandNumber | int8 | 0-based band number to use from | |
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| 116 | | | | the set available in the external | |
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| 117 | | | | file | |
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| 118 | +---------------+-------------+-----------------------------------+ |
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| 119 | | path | string | null-terminated path to data file | |
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| 120 | +---------------+-------------+-----------------------------------+ |
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