Guillaume: 1 revision

2008-12-03T10:27:07Z

1 revision

192.168.20.177: /* Grid Data 3D */

2008-01-31T16:55:38Z

‎Grid Data 3D

New page

== Overview ==
Grid Data items relate to 2D or 3D information referenced to a grid. Grid data is stored in an ASCII text file and has multiple and flexible formatting options. In order to view a Grid Data file in [[Mohid GIS]] the file must contain [[grid]] information. In Mohid, the grid information is not used except for [[bathymetry file]] to [[Mohid Water]], or the input [[topography]] file to [[Mohid Land]] where the simulation domain is defined. Grid Data items can be used to initialize 2D or 3D fields (e.g. temperature, salinity) via [[Module_FillMatrix#ASCII_Grid_Data_file|Module FillMatrix]].

== Header Section ==
The header section contains some specifications on the type of organization of the information.

[[FILL_VALUE]] : -9.9e15
[[TYPE_ZUV]] : z

[[FILL_VALUE]] specifies a value for points with no data.

[[TYPE_ZUV]] specifies if the data is located in the center of the grid cell or referenced to the faces of the grid cell. It can be '''z''' for centered data, '''u''' for east-west faces or '''v''' for north-south faces.

== Data Section ==

=== Grid Data 2D ===
The data section contains the values of the Grid Data item. The data is stored inside a block defined by the following keywords: '''<BeginGridData2D>''' and '''<EndGridData2D>'''. Note that these keywords are case sensitive.

====Filling data for all grid cells====
You can specify the values by giving a list of all values of all the grid cells. Each value must be stored in a single line. The values are read from the lower left corner to the upper right corner of the grid that is values reading is done by row-column order. The first grid data values are read in the following order: (ILB, JLB), (ILB, JLB+1), … (ILB, JUB), (ILB+1, JLB), …, (IUB, JUB-1), (IUB, JUB). Note that the index “i” refers to the Y-axis and the “j” index to the X-Axis. In this case, if you have a (IUB x JUB) grid then the list must have (IUB x JUB) values.

'''<BeginGridData2D>'''
12.5
13.1
10.2
...
...
'''<EndGridData2D>'''

====Filling data for some grid cells only====
If you don't want to define all the values in the grid but only in a subset of cells in the grid (for example, if you want to simulate a bump in a flat bathymetry. Everywhere is 1000 m depth except in the bump area, so you want to define only the bump area); then you can also use '''''"i j value(i,j,:)"'''''. Values not specified in the list will be given the [[DEFAULTVALUE]].

'''<BeginGridData2D>'''
2 1 12.8
2 2 13.4
5 1 11.3
.. .. ..
'''<EndGridData2D>'''

If the array is 3D and you wish to specify that in the vertical direction all the values are constant then use '''''i j value(i,j,:)'''''. In the following example, if you have 3 layers, then grid cells (1,1,1), (1,1,2) and (1,1,3) will all be given the value of 10.2. Values not specified in the list will be given the [[DEFAULTVALUE]].

'''<BeginGridData2D>'''
2 1 12.8
2 2 13.4
5 1 11.3
.. .. ..
'''<EndGridData2D>'''

=== Grid Data 3D ===

The data section contains the values of the Grid Data item. The data is stored inside a block defined by the following keywords: <BeginGridData3D> and <EndGridData3D>. Note that these keywords are case sensitive.

Between these keywords, for each grid cell, a value must be supplied (.e.g. for the [[bathymetry file]] write the bathymetry value).

If the array is 3D and you which to specify that in the vertical direction the values are constant then use ''"i j value(i,j,:)"''. In the following example, if you have 3 layers, then grid cells (1,1,1), (1,1,2) and (1,1,3) will all be given the value of 10.2. Values not specified in the list will be given the [[DEFAULTVALUE]].

'''<BeginGridData3D>'''
1 1 10.2
1 2 12.3
2 5 10.7
.. .. ..
'''<EndGridData3D>'''

If the array is 3D and you wish to specify to each grid cell a specific value the use ''i j k value(i,j,k)''. Values not specified in the list will be given the [[DEFAULTVALUE]].

'''<BeginGridData3D>'''
1 1 1 10.2
1 1 2 10.1
1 1 3 9.9
1 2 1 12.3
.. .. .. ..
'''<EndGridData3D>'''

You can also specify the values by giving a list of all values of all the grid cells. In this case, if you have a (IUB x JUB x KUB) grid then the list must have (IUB x JUB x KUB) values.

'''<BeginGridData3D>'''
10.2
10.1
9.9
12.3
12.1
...
'''<EndGridData3D>'''

[[Category:Input Data Formats]]

← Older revision	Revision as of 10:27, 3 December 2008
(No difference)

Grid Data - Revision history

Guillaume: 1 revision

192.168.20.177: /* Grid Data 3D */