t.vect.observe.strds.1grass man page

t.vect.observe.strds — Observes specific locations in a space time raster dataset over a period of time using vector points.

Keywords

temporal, sampling, vector, time

Synopsis

t.vect.observe.strds
t.vect.observe.strds --help
t.vect.observe.strds input=name strds=name[,name,...] output=name vector_output=name columns=string[,string,...] [where=sql_query] [t_where=sql_query] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags

--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog

Parameters

input=name [required]
Name of input vector map
Or data source for direct OGR access
strds=name[,name,...] [required]
Name of the input space time raster datasets
output=name [required]
Name of the output space time vector dataset
vector_output=name [required]
Name of the new created vector map that stores the sampled values in different layers
columns=string[,string,...] [required]
Names of the vector columns to be created and to store sampled raster values, one name for each STRDS
where=sql_query
WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and inhab >= 10000
t_where=sql_query
WHERE conditions of SQL statement without ’where’ keyword used in the temporal GIS framework
Example: start_time > ’2001-01-01 12:30:00’

Description

The module t.vect.observe.strds is used to observe specific locations in a space time raster dataset over a period of time using vector points. The first input is a vector map layer with vector points. The second input is one or several space time raster datasets (STRDS) that should be sampled over time at the vector point positions. The space time raster dataset will be sampled over its whole temporal extent (from start to end). The range can be adjusted using the temporal where condition t_where. The temporal "where" will only work as expected when just one STRDS is to be sampled. If more than one STRDS are to be observed, a column name must be specified for each input space time raster dataset.

As results a new space time vector dataset is generated that contains a single (new) vector map that links to as many time stamped attribute tables as raster map layer are present in the input space time raster dataset. Hence, for each time step in the space time raster dataset a new attribute table is created. The GRASS GIS Temporal Framework allows to time stamp attribute tables that can be linked to a single vector map layer.

The module v.what.rast is used internally for sampling the time stamped raster map layers. All sampled values of a single time stamped raster map layer are written into a new time stamped attribute table.

Use t.vect.db.select to print attribute values of the space time vector dataset to stdout.

Example

The example show how to create a space time vector dataset and a vector layer starting from a point vector and a space time raster dataset:

t.vect.observe.strds input=precip_30ynormals_3d strds=tempmean_monthly \
                     output=precip_stations vect=precip_stations_monthly \
                     columns=month
t.info precip_stations type=stvds
 +-------------------- Space Time Vector Dataset -----------------------------+
 |                                                                            |
 +-------------------- Basic information -------------------------------------+
 | Id: ........................ precip_stations@climate_2009_2012
 | Name: ...................... precip_stations
 | Mapset: .................... climate_2009_2012
 | Creator: ................... lucadelu
 | Temporal type: ............. absolute
 | Creation time: ............. 2014-12-02 00:42:39.187615
 | Modification time:.......... 2014-12-02 00:42:55.215169
 | Semantic type:.............. mean
 +-------------------- Absolute time -----------------------------------------+
 | Start time:................. 2009-01-01 00:00:00
 | End time:................... 2013-01-01 00:00:00
 | Granularity:................ 1 month
 | Temporal type of maps:...... interval
 +-------------------- Spatial extent ----------------------------------------+
 | North:...................... 306221.830194
 | South:...................... 27606.895351
 | East:.. .................... 917004.829165
 | West:....................... 151768.568246
 | Top:........................ 1615.44
 | Bottom:..................... 2.4384
 +-------------------- Metadata information ----------------------------------+
 | Vector register table:...... vector_map_register_be074525097c4088997c9a1979f17065
 | Number of points ........... 6664
 | Number of lines ............ 0
 | Number of boundaries ....... 0
 | Number of centroids ........ 0
 | Number of faces ............ 0
 | Number of kernels .......... 0
 | Number of primitives ....... 6664
 | Number of nodes ............ 0
 | Number of areas ............ 0
 | Number of islands .......... 0
 | Number of holes ............ 0
 | Number of volumes .......... 0
 | Number of registered maps:.. 49
 |
 | Title:
 | Observaion of space time raster dataset(s) tempmean_monthly
 | Description:
 | Observation of space time raster dataset(s) tempmean_monthly with vector map precip_30ynormals_3d
 | Command history:
 | # 2014-12-02 00:42:39
 | t.vect.observe.strds input="precip_30ynormals_3d"
 |     strds="tempmean_monthly" output="precip_stations"
 |     vect="precip_stations_monthly" columns="month"
 |
 +----------------------------------------------------------------------------+
v.info precip_stations_monthly
 +----------------------------------------------------------------------------+
 | Name:            precip_stations_monthly                                   |
 | Mapset:          climate_2009_2012                                         |
 | Location:        nc_spm_temporal_workshop                                  |
 | Database:        /grassdata                                                |
 | Title:           North Carolina 30 year precipitation normals (3D)         |
 | Map scale:       1:1                                                       |
 | Name of creator: neteler                                                   |
 | Organization:                                                              |
 | Source date:     Wed May  9 14:32:39 2007                                  |
 | Timestamp (first layer): none                                              |
 |----------------------------------------------------------------------------|
 | Map format:      native                                                    |
 |----------------------------------------------------------------------------|
 |   Type of map: vector (level: 2)                                           |
 |                                                                            |
 |   Number of points:       136             Number of centroids:  0          |
 |   Number of lines:        0               Number of boundaries: 0          |
 |   Number of areas:        0               Number of islands:    0          |
 |   Number of faces:        0               Number of kernels:    0          |
 |   Number of volumes:      0               Number of holes:      0          |
 |                                                                            |
 |   Map is 3D:              Yes                                              |
 |   Number of dblinks:      49                                               |
 |                                                                            |
 |   Projection: Lambert Conformal Conic                                      |
 |                                                                            |
 |               N:     306221.830194    S:      27606.895351                 |
 |               E:     917004.829165    W:     151768.568246                 |
 |               B:            2.4384    T:           1615.44                 |
 |                                                                            |
 |   Digitization threshold: 0                                                |
 |   Comment:                                                                 |
 |                                                                            |
 +----------------------------------------------------------------------------+

See Also

t.create, t.info, t.vect.db.select, t.vect.what.strds

Author

Sören Gebbert, Thünen Institute of Climate-Smart Agriculture

Last changed: $Date: 2016-02-09 18:21:24 +0100 (Tue, 09 Feb 2016) $

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