Hot answers tagged buffer
10
ArcGIS is utterly woeful for dissolving/merging. We had to do a buffer/merge for 3 million points recently and soon gave up on using ArcGIS -- their help desk didn't have much clue either. Postgres did it in less than an hour using the st_union function.
see http://blog.cleverelephant.ca/2009/01/must-faster-unions-in-postgis-14.html
10
The buffer size is always applied in the layer CRS units. Therefore, the layer CRS has to use meters if you want to buffer in meters.
You don't need ftools to change the CRS.
Open the original layer in WGS84 CRS.
Right-click in layer list and select "Save as ...". (DON'T change the CRS in layer options!)
Set the target CRS to NAD83/Maryland and save.
...
9
You can use the "Intersect" tool on the buffer and land use layers. This should create a third layer where buffers are "cut out of" the land use polygons. Then you can calculate the area of the resulting polygons using Field Calculator.
Village buffer before
and after the Intersect operation and calculation of area using Field Calculator:
Divide by ...
8
Proper one-sided buffers were supposed to have landed in 1.5, but it looks to me that while the styles did land, sidedness didn't make it in. There is however a current patchset which exposes GEOSSingleSidedBuffer and performs the one-sided buffer as expected, under the name ST_OffsetCurve; see further background in ticket #413. In use:
select ...
8
Try these steps with ArcMap 10:
Buffer your point feature (ArcToolbox > Analysis Tools > Proximity >
Buffer). Make sure to select the correct distance in the Linear
unit box.
Input your newly created buffers into the Feature Envelope to
Polygon tool (Data Management Tools > Features > Feature Envelope to
Polygon). Make sure to select the "Create multpart ...
7
You don't say which software you're using, but the thing you're looking for is Voronoi polygons (AKA Theissen polygons). This is the set of polygons such that any point within a polygon is nearest to its seed point.
You will find that the polygons tessellate, which might be a problem if your offices have a maximum distance of responsibility. If that is the ...
7
i dont know is this work for you, but you can do:
.
1.Select your layer with clicking on it
2.From Editor toolbar, select Start Editing
3.in Editor Menu, select Buffer
4.Write Negative Distance Amount for inner buffer...
.
Without Inner Buffer:
With Inner Buffer:
manual inner buffer solution which i use.
i hope it helps you...
7
A possible solution would be to create your "normal" round buffers using the standard ESRI buffer tool with whatever radius you would like and then performing a Feature Envelope To Polygon on that resulting feature class of buffers. This creates a square envelope feature around the extent of each feature. Feature Envelope to Polygon is located within Data ...
7
Defining a line's side is rather straight forward on an orientable surface, which a 2D plane in a GIS is. If you define a start point and an end point for a line, you can unambiguously define "left" and "right" sides. This is the case even if the line crosses itself.
From a more practical standpoint, simple workflow for creating a one-sided buffer includes ...
6
Use the Buffer Tool from the Analysis toolbox and enter a negative value for the buffer distance. Pick OUTSIDE_ONLY for the side type and then dissolve on the relevant attributes.
Requires Arcinfo.
6
Forgive me if I'm missing something, but it seems that all you need here is your point shapefile and the buffer tool which is located at: Analysis Tools -> Proximity -> Buffer
Specify your input points and a buffer distance. Use the "Show Help" pane in the tool if you need guidance on some of the tool options.
6
As Underdark comments ST_Dwithin is the recommended way of finding geometries at a distance. In many other gis-systems the buffer method is the only way but building buffers is quite costly.
But there is other use cases when you need to buffer. One reason can be to visualize a buffer. If you for instance wants to show the area closer than 100 meters from a ...
6
For this application, I would use an Azimuthal Equidistant projection centered in the middle of your source points. This projection has the nice feature of all radial distances around the center of the projection being accurate.
That particular projection is not part of QGIS standard projections. You can define your own using Settings/Custom CRS with the ...
5
Because this question is buried in comments, let's assemble them in one place to see what's the issue:
(1) I have created shapefiles that identify the location of operational incinerators and areas that have refused incinerators planning permission and wish to compare the buffers of each.
(2) I also wish to ... see if there is any correlation ...
5
You can perform operations with WKT you return from consultations in postgis
SELECT ST_ASTEXT(ST_Buffer(ST_GeomFromText('POINT(100 100)'), 500));
you recieve WKT and use Openlayer to convert the wkt to geometry and feature. for example : var elemento = New OpenLayers.Format.WKT().read('textWktFromRecordColumn');
I hope it helps. greetings
5
ArcGIS is the software suite name, whereas ArcView, ArcEditor, & ArcInfo are licensing levels for ArcGIS.
ArcView has limited buffer options, and ArcInfo has the full, advanced buffer options (see bullet point #4 under "Usage Tips").
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=buffer_%28analysis%29
5
Hallo
Here I think is a little fun way of doing it in PostGIS. This I think could be extended so the expansion follows some linestring representing the current. But now it just expands in one direction.
It iterates 50 times and for each iteration takes the polygon from last iteration, moves it, bufferes it (simplifies it to make things run smother) and ...
5
OK, how I did this, is loop through creating ring buffers on objects, and saving the output as a new featureclass in a standlone datasets collection. I then merged the featureclasses, like so:
tmp_merge = "path to area"\+ "tmp_merge"
final_out_path_agg = final_staging + "_Agg"
final_out_path_simp = final_staging + "_Simp"
#check if files exist and ...
5
Select by Location with negative 1000m buffer, switch selection, select by location "Within" again from reversed selection set
Step 1:
Selection method: Select Features From (default)
Target Layer: Houses
Source Layer: Big Polygon
Spatial Selection Method: Target layers(s) features intersect the Source layer feature (default)
Apply a search distance = ...
5
Here is a solution which is running quite fast (around 15 seconds for a 5 million random points which i created for Texas State). I normalized the multipoint input and it is giving satisfactory output. I am using Topology Framework .NET. It is similar to NetTopologySuite. Maybe you can do the same with NetTopologySuite as well.
My solution (console ...
5
I would recommend you use ST_HausdorffDistance() to caluclate the similarity of your GPS tracks; using ST_Buffer() or ST_Distance() will cause you issues if your tracks get near to each other at some point, but otherwise are divergent.
Hausdorff distance is a bit funny to get your head around, but it's ideal for this sort of query, and after a bit of trial ...
5
The comments suggest the 5% does not need to be attained with high accuracy. (If it does, it will take a long time to buffer a million polygons!) We can therefore invoke the Pizza Principle: linearly rescaling a 2D feature by a factor a rescales its area by a^2.
Here's how the reasoning goes:
When the shape is not too convoluted--especially if it's ...
5
When you make a buffer you can choose to dissolve (or not) the buffers. When you check dissolve, the overlapping buffers will be merged together. So there will be no double count when calculating the area.
Now you can calculate the area with the fieldcalculator. See: How to calculate polygon areas in QGIS?
5
There are 2 ways you could approach this; server side or client side. The approach you take will depend on whether you want the processing overhead on the client or on the server (or even if you have access to a backend server like GeoServer).
Method 1: Client Side
There is a pure JavaScript port of the Java Topology Suite called JSTS which contains ...
5
As MappaGnosis indicated, you could write a little script for this. Here's one called polygonbuffer which takes three arguments: The output file name, the radius of your buffer, and the number of corners of the polygons.
Open a Python console in QGIS, paste the script and press enter to define the function, then call using something like ...
4
This sample creates two polygons on either side of a linestring. It requires PostGIS 1.5 or greater. I'm not sure how well it will cope with lines that cross themselves.
SELECT ST_AsText(geom)
FROM ST_Dump ((
SELECT
ST_Polygonize(GEOMUNION(ST_Boundary(ST_Buffer(the_geom, 0.5, 'endcap=flat join=round')), the_geom)) AS buffer_sides
FROM
(SELECT ...
4
Buffering is allowed in all licences (ArcView, ArcEditor & ArcInfo)
Full License Matrix for 9.3 is here:
http://www.esri.com/library/brochures/pdfs/arcgis93-functionality-matrix-list.pdf
4
Can you not use an iterator in ModelBuilder? for buffering multiple distances?
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00400000001n000000.htm
4
Yes this is possible Katherine.
Basically what you need to do is to add a column to your plants shapefile that corresponds to the size of that buffer.
You could also add fields for the amount of corn each plant needs and other useful information to help you calculate the size of the buffer.
You, of course, will need to fill it with something meaningful. ...
4
As someone else already pointed out, you can use the Batch option by right-clicking the tool in Toolbox. Otherwise, it's hard to know how best to batch it without knowing more about the feature classes and their locations (are they all in the same workspace? are they the only feature classes in that workspace?) and the type of buffers you want to create ...
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