NAME

KEYWORDS

SYNOPSIS

DESCRIPTION

• The data is sorted according to point names to keep points from separated layers together.
• The script scans input file and creates separate files for each layer. Layers are distinguished by point names that provide information on layer name, vector type and point identifier. More detailed information about how to draft point names in your dataset (during data acquisition or in post-processing) is provided in Notes section.
   
• Line and polygon data are converted to standard format (input data should respect topological rules to get geometrically correct layers).
   
• Then, new vector layer is created using v.in.ascii. Points are stored in point layer; lines and polygons in line layer at this moment. Lines that store polygon data are converted to new polygon layer using v.centroid.
   
• Attribute table is maintained for line and polygon layers (points are imported in point format with the attributes as well).
  • in case of line layers, categories are added at first using v.category,
  • attribute table is created using v.db.addtable,
  • column that stores layer name is updated using v.db.update.
     
• There is an option to merge the features by v.patch using various patterns to detect desired layers. For more details, see Notes.
   
• Finally, v.clean is performed to clean the topology if any layers have been merged.
• If desired, conversion to DXF file is performed as well.

NOTES

Input data

• only input data in point format is accepted. The file should contain just point identifier (see next item) and coordinates in two- or three-dimensional space.

  		Point_name		easting	northing	[elevation]
  		name.code.number	x	y		[z]
  		

  It does not depend on the coordinate order in the input file. The user can set up number of column for each coordinate (as in v.in.ascii).
   
• Point name provides information that is substantial for new layer creation - name and desired type of vector. Required format of the point name looks like this:

  			layer_name.code.number
  		

  Items are separated by dots. To get correct results, please remove or replace all redundant dots in the input data.

  name	any short, descriptive name as you wish your layer to be named. Please do not use spaces or dots.
  code	information about vector type of the new layer (point, line, polygon). You may define your own codes that refer directly to the geometry (e.g. point, line, poly etc. including various abbreviations). Or you may specify that e.g. tree, bush etc. are codes for point features, river, profile etc. refer to line segments and lake and house represent new polygon layers.
  number	simple identifier of the point in the layer (preferably plain numbering)

• if using a header or columns' names, refer this in skip parameter
   
• if necessary to merge any layers, please give them a name with specific prefix, which should be used as merging rule as well. Merging rule that is based on suffix or another part of the layer name is not recognized.
   
• if the module crashes suddenly during large dataset processing, it might be caused by incomplete data writing to the layer input file. Please divide input data into several smaller files (probably depends on your computer performance).

Conversion to DXF

• the name of DXF file. The file will be written into the output directory.
• drawing units. Default value: metric. Another option: imperial.
• height of the text. Default value: 0.0 (the height will be derived as a fraction (0.003) of longer side of a rectangular mapset region)

EXAMPLES

v.in.survey input=test_data.dat separator=tab skip=1 easting=2 northing=3 pt_rules=pt ln_rules=ln poly_rules=poly outdir=NC_test

Fig. 1: Imported features with broken areas	Fig. 2: Lines with the directions	Fig. 3: Imported features with correct areas

To fix broken areas, original lines have been merged using v.edit according to their categories. Then points have been exported again and they were copied to enclose each area - respecting lines and the directions as might be seen in Fig. 2. In Fig. 3, there is shown that areas fit well too after editing input file.

If it is necessary also to merge some of the layers, then merging rules can be set up:

	v.in.survey input=test_data_small_corrected_soils.dat separator=tab easting=2 northing=3 pt_rules=pt ln_rules=ln poly_rules=poly \ 
	outdir=NC_test_small_merge merge_lyrs=road,soil

Fig. 1: DXF drawing together with the labels (north arrow and scale have been added later)

The colours in DXF drawing have been set up automatically. In this case, labels of roads and elevation labels of soil types have been switched of because of too large amount of the data. Examples of more detailed exports can be seen in (Stopkova, 2016).

WARNINGS

ERROR MESSAGES

Input data:

ERROR: Please rename point in line i according to the script request in format 'lyr_name.vect_type_code.number'.
Point name is expected to provide information in particular format. Edit point name in i^th line of the input file and run script again.

ERROR: Please do not use SQL forbidden characters in your input data. Remove all 'char' from the file.
Any special characters are not allowed in the data. Please use just dots to separate parts of point names. If necessary, make the names more clear using underscores.

ERROR: Not enough points to make line layer <layer>.
ERROR: Not enough points to make polygon layer <layer>.
These errors may refer to:

• a typographical mistake in particular point's name. Edit point's name in the input file and run script again.
• mixed layers. See (Stopkova, 2016) for more details. Edit point's name in the input file and run script again.
• broken geometry (just one point referring to a line or less than three points referring to a polygon). Please remove these points or edit their vector type (middle part of point name) to refer to a point.

Script settings:

ERROR: Vector layer layer is not point, neither line, nor boundary. Please check your input data and rules that you have typed in.
Vector type information (middle part of the point name) does not match to any of geometry codes that you have entered. Please compare input settings with point names in the data file, complete input settings (or edit input data) and run the script again.

ERROR: Please redefine merging option <char>. Different vector types match this rule.
Merging different vector types is not allowed. This might be matter of comparing layer names with too free rules:

Tab. 1: Example of too free rules for merging layers

river		river -> river_stream
river_stream_Danube		river_area_Danube
river_stream_Vah		river_stream_Vah
river_stream_Hron		river_stream_Hron

In the left column, there are summarized line objects that should be merged to one single layers called river. This merge is possible, as all the features are represented by line. In the right column, there are summarized rivers as well. But they cannot be merged, because the Danube river is represented by polygon and the rest of the features are lines. It would be better to use merging criteria river_stream to separate just line object to be merged.

Files:

Output layers:

Empty layer (not reported in command output): if the layer exists but is empty, please check the input points. This might happened because of wrong point order (especially if the point order has been edited).

DXF conversion:

SEE ALSO

AUTHOR

Last changed: $Date: 2016-10-06 10:10:51 +0200 (Thu, 06 Oct 2016) $

SOURCE CODE

Available at: v.in.survey source code (history)

Main index | Vector index | Topics index | Keywords index | Graphical index | Full index

© 2003-2019 GRASS Development Team, GRASS GIS 7.4.5svn Reference Manual