The Transpose Bit function unpacks the bits of the input pixel and maps them to specified bit locations in the output pixel. The purpose of this function is to manipulate multiple bit sequences from an input, such as the Landsat 8 quality band products.
Notes
Bit Pattern
The bit pattern dictates which bits within the quality band will be rearranged. Landsat 8 has a quality band that is 16 bits. Each of these bits, or in some cases two adjacent bits, have a specific meaning.
| Bit Pattern | Bits involved | Values |
|---|---|---|
Landsat 8 Designated Fill | 0 | 0 = Image data 1 = Fill data |
Landsat 8 Dropped Frame | 1 | 0 = Image data 1 = Dropped frame |
Landsat 8 Terrain occlusion | 2 | 0 = Normal data 1 = Terrain data |
Landsat 8 Water | 4–5 | 00 = None or unset 01 = 0%–35% confidence of water 10 = 26%–64% confidence of water 11 = 65%–100% confidence of water |
Landsat 8 Cloud Shadow | 6–7 | 00 = None or unset 01 = 0%–35% confidence of cloud shadow 10 = 26%–64% confidence of cloud shadow 11 = 65%–100% confidence of cloud shadow |
Landsat 8 Vegetation | 8–9 | 00 = None or unset 01 = 0%–35% confidence of vegetation 10 = 26%–64% confidence of vegetation 11 = 65%–100% confidence of vegetation |
Landsat 8 Snow/Ice | 10–11 | 00 = None or unset 01 = 0%–35% confidence of snow or ice 10 = 26%–64% confidence of snow or ice 11 = 65%–100% confidence of snow or ice |
Landsat 8 Cirrus | 12–13 | 00 = None or unset 01 = 0%–35% confidence of cirrus 10 = 26%–64% confidence of cirrus 11 = 65%–100% confidence of cirrus |
Landsat 8 Cloud | 14–15 | 00 = None or unset 01 = 0%–35% confidence of cloud 10 = 26%–64% confidence of cloud 11 = 65%–100% confidence of cloud |
User Defined |
Choose the bits you want to rearrange. For example, If you choose the Landsat 8 Water option, you want to bring bits 4 and 5 to the 0 and 1 bit location, within the output.
In the image above, the Landsat 8 Water transpose method takes the fourth and fifth bits, and puts them into the zero and one bit location in the output.
Constant Fill
A constant fill first allows the bits to rearrange as specified by the bit pattern and fills the other bits in with the constant fill.
In the image above, the first set of bits represent the input. The middle set of bits represent the constant fill. The third set of bits represent the output. Once again in this example, the Landsat 8 Water method has been selected. The output is ordered such that the fourth and fifth bits will be placed in the zero and one bit output location. The rest of the output is filled with the constant fill that was chosen.
Fill Raster
A fill raster first allows the bits to rearrange as specified by the bit pattern and fills the other bits in with the specified fill raster.
In the image above, the first set of bits represent the input. The middle set of bits represent the selected fill raster. The third set of bits represent the output. Once again in this example, the Landsat 8 Water method has been selected. The output will be ordered such that the fourth and fifth bits will be placed in the zero and one bit output location. The rest of the output is filled with the chosen Fill Raster.
Parameters
| Parameter name | Description |
|---|---|
| Raster | The input raster to unpack and remap. |
| Generate Fill Raster from Constant | Generate a fill raster using a constant value:
|
| Constant Value | An optional value that will be used to fill in all bits that are not involved in the transpose. This parameter is exposed when the Generate Fill Raster from Constant parameter is set to Yes. |
| Fill Raster | Specify a raster dataset to be used to fill in all bits that are not involved in the transpose. This parameter is exposed when the Generate Fill Raster from Constant parameter is set to No. |
| Bit Pattern | Choose the type of transpose to perform or specify a custom one:
|
| Output Bit and Input Bit | A read-only table that shows the output bits and the inputs that will be in their place. |