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GRID to GRID draft: Difference between revisions

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=Introduction=
The grid_to_grid.exe is a utility that can be used to perform a range of operations on gridded files. The input grids can be a combination of GeoTIFF (.tif), ESRI ASCII (.asc), binary float (.flt) geopackage (.gpkg), NetCDF (.nc) and Cloud Optimised GeoTIFFs (.cog) grids, all of which can be input and output from TUFLOW and any of the format can be set as output from the utility.<br>
For some options (such as processing maximums or differences) the input files must be of the same row/column dimensions.<br>
 
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==Transform==
Transforms the values using a simple y = mx + c approach. theThe multiplier (m) is specified with flag '''-trans_m<value>'''. The add value (c) with flag '''-trans_c<value>'''. Only one valuesvalue is required to be specified.<br>
Example:
*Multiplies all values by 0.3048.<br>
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==Classify==
Classifies the grid based on the input classifications. The output file is a classified grid. The classification .csv file should have two columns, cutoff value and name (in that order). The first line in .csv treated as a header line and ignored. Any values over the greatest cutoff with be outputted to class "above".<br>
{| class="wikitable"
 
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*Outputs a classified grid, based on the cut off values and names in the "classifications.csv".<br>
:<tt>grid_to_grid.exe -classify classifications.csv results_VMax.tif</tt>
*If using vertical mapper the -grc option can be used to create the tifflt file in classified grid format,. inIn this format, rather than storing a numerical value when interrogating an area, a label is returned. This format is not recognised by ArcMap or QGIS. If using the grc option it is also possible to specify the desired RGB (red, green, blue) values for the output grid in the .csv file used for the classification. The RGB values should be specified in the 3-5th columns of the .csv file.<br>
:<tt>grid_to_grid.exe -RGB -grc -classify depth_classify.csv results_dMax.tifflt</tt><br>
 
:{| class="wikitable"
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==Extract Breaklines from DEM==
'''"-brkline <gis file in 2d_zsh format>"'''<br>
Extracts elevations from a DEM for breaklines in the 2d_zsh format. This GIS input should have four attributes, z, dz, width and shape_options, as described in the <u>[https://docs.tuflow.com/classic-hpc/manual/latest/ TUFLOW Manual]</u>. For the utility the '''dz''', '''shape_width''' and the '''shape_options''' are used. Valid shape_options are "Max" and "Min" or blank (average used). The utility will extractextracts an elevation at each <u>vertex</u> along the line.<br>
Depending on the line width and DEM cell size, the following methods are used:<br>
* If the width is set to 0, the closest DEM value to the vertex is used. If a "shape_option" is specified, this is ignored.
* If the width is greater than 0, but less than 1.5 times the DEM cell size, the four DEM values surrounding the vertex are used. If max or min is specified in the "shape_option" the max or min of the four values is used. If max or min option is not specified (attribute is blank), the average of the four values is used.
* If the width is greater than 1.5 times the DEM cell size, at each vertex a buffer region (search radius) is created and all non null DEM values within the buffer object are processed. The diameter of the buffer region is equal to the width specified. If max or min option is not specified, the average of the values within the region is used. These buffer regions are outputted as a separate file, if '''"-check"''' switch is specified in the batch command.<br>
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'''"-fuzzy <input grids>"'''<br>
A fuzzy map can be used when comparing a large number of simulations.<br>
For each input grid (or scenario) the grid is classed as either 1 if the results grid is wet or 0 if dry. The total score for each grid cell is is calculated and then divided by the total number of input grids. A value of 1 indicates that the cell was wet in each simulation ,a value of 0 is dry in all simulations. Grids with a value of 0.5 are most sensitive.<br>
This can be useful for quantifying the sensitivity of the model to parameters.<br>
Example:
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|Read GIS XS == <1d_cut GIS file>|| Reads the cross-section cut lines, these are described above.
|-
|Read GIS FLC == <GIS file>|| Optional GIS layer of polygons that can be used to specify form loss coefficients to the 1d_nwk layer. A single GIS (float) attribute is required. A FLC value of greater than 0 will be split between all 1d_nwk channels within the region. A FLC value of less than 0, will apply the absolute value to all channels within the polygon. For example if an FLC value of -0.1 is specified, all channels that fall within the polygon will have a form_loss attribute of 0.1. If a channel falls within multiple polygons, the form loss values will be added.
Reads the polygons off losses from GIS layer. cross-section cut lines, these are described above.
|-
|Set XS dx == <distance>|| Sets the default distance across section to extract elevations and materials data. This can be specified on the cut lines as detailed above.
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The out nodal area table extends from the minimum to the maximum elevation in the DEM. A user defined minimum value can be specified using the "Skew" attribute of the GIS region.<br>
Example:
*<tt>grid_to_grid.exe -na 1d_na_storage_Rstorage_R.shp DEM_1m.tif</tt>
 
==Calibration Points==
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* An SRC grid: a grid listing which source input grid the median result value came from (a corresponding .csv file is also written as a legend)<br>
Example:
*<tt>grid_to_grid.exe -statMedian Q100_30min_TP1_h.tif Q100_30min_TP2_h.tif Q100_30min_TP3_h.tif Q100_30min_TP4_h.tif Q100_30min_TP5_h... Q100_30min_TP10_h.tif </tt><br>
 
[[File: asc_to_asc_statsMedian_eg.PNG|1000px|]]<br>
<br>
Note, the median value for thatthe cellexample wasbelow dryis (a 'NULL') value, then the output wouldis bea dry cell. For example, 7 out of the 10 inputs are dry at athis particular locationcell. Once theythe outputs are ordered them (with NULL showing at the lowest spots), then the median (6th) value for thisthe cell is 'NULL' (dry) and the source would be 8, as shown below. Therefore, at this location you would see a dry cell in the median output, and '8' inis the source grid output.
<br>
[[File:A2A median.png|400px]]<br>
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The utility outputs one grid:
* A Frac grid: the resulting Fractionfraction value<br>
Example:
*<tt>grid_to_grid.exe -statFrac Q100_30min_*_h.tif</tt><br>
 
==="-statMin"===
The -statMin flag outputs the minimum value at each grid cell from all the input grids. This flag is analogous with the [[#Minimum|-Min]] operation flag.
 
The utility outputs two grids:
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==="-statRank<integer id>"===
The -statRank<integer> flag outputs the ''n<integer>'' ranked value at each grid cell from all the input grids. All the input grids are considered, regardless of if the grid cell is dry in some of the input grids (dry areas are still ranked as low e.g. Rank1, Rank2 and so on). For example, if the number of input grids is 10, at each grid cell the values are ranked lowest to highest (from 1 to 10). -statRank8 will output results taken from the 8th ranked grid. In this example, -statRank1 is equivalent to ''Min'', -statRank10 is equivalent to ''Max'', and -statRank6 is equivalent to ''Median''. The Rank flag allows additional functionality that lets users extract results in between those that are pre-programmed.
 
The utility outputs two grids:
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==Flood Extent==
'''"-wl <wl_file>fe"'''<br>▼
Returns a simple grid with value of 1 where the input grid has an active, non-zero value.<br>
Example:
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==Remap==
'''"-wl <wl_file> -dem <dem_file>"'''<br>▼
RemapRemaps acoarser resolution water level grid to a higherfiner resolution DEM.<br>
▲'''"-wl <wl_file>"'''<br>
Sets the coarser resolution water level grid to remap from.<br>
▲'''"-dem <dem_file>"'''<br>
Sets the finer resolution DEM.<br>
The default interpolation method is TIN. But "-idw_npt<number of points>" flag can be used to change the interpolation method to IDW and set the number of points used for IDW interpolation (default is 12).<br>
Example:
*TheRemaps utilitywater canlevel also remap additional map output grids (e.g. velocity, hazard and others)grid to the resolution of the DEM file, e.g.:<br>
:<tt>grid_to_grid.exe -remap -wl lowres_h.tif -dem DEM_highres.tif</tt>
*The utility can also applyremap adepth bufferoutput distancegrids or add freeboard. For example,to the below applies a buffer distanceresolution of 20m, and adds a freeboard of 0.2m to the original water levelDEM grid.file:<br>
:<tt>grid_to_grid.exe -remap -wl lowres_h.tif -dem DEM_highres.tif lowres_v.tif lowres_hazardlowres_d.tif</tt>
*The utility can also apply a buffer distance or add a freeboard. The below applies a buffer distance of 20m, and adds a freeboard of 0.2m to the original water level grid.<br>
:<tt>grid_to_grid.exe -remap -fb0.2 -bd20 -wl lowres_h.tif -dem DEM_highres.tif</tt>
 
Note that, for any output types other than depth, this utility does NOT interpolate the result from the coarser grid to the finer grid, but only extends/reduces the output extent to the dry/wet extent. More discussions on this function is documented here <u>[[TUFLOW_Remapping | TUFLOW Remapping Tool]]</u>.<br>
 
 
=GPKG and NetCDF=
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