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13

Yes is the short answer. You can do this in GRASS using r.viewshed. However, it sounds very much like you are doing some Windfarm ZTV (Zones of Theoretical Visibility) analysis. If that is correct, you could also try OpenWind. This is an excellent and free utility and may be right up your street. It doesn't have the full-on capabilities of the big three ...


7

As you would have seen from the referenced GIS SE question, there doesn't appear to be much in the way of viewshed stand-alone packages at least in the Open Source market beyond SAGA and GRASS GIS. Apart from writing a wrapper around the code for these algorthims you may end up implementing viewshed yourself unfortunately. (Though I would love to be ...


6

I'm assuming what you're after as a viewshed analysis tool. Check the wikipedia page for a brief introduction. As far as i'm aware QGIS doesn't have this built in however there is a plugin available at http://pyqgis.org/repo/contributed . Not sure if this tool works with vector data however, but i suppose you could always do a conversion. Similarly for ...


6

Here's two examples. First, a video showing off the new QGIS Globe plugin, but also showing PostGIS's 3d functions: http://vimeo.com/54776907 Second, an example of viewshed analysis using PostGIS, R, and GRASS: http://www.dimensionaledge.com/main/postgis/viewshed-analysis-in-postgis-using-plr-and-grass/


5

I've never used the viewshed tool so I can't speak to the specifics of using that tool, however in regards to your suggestion in this question I will add an answer here to build on KHibma's solution. The first thing we need to address is the format of your SQL query: "[OID] = count". As it stands, this query will fail since "count", as represented here, is ...


5

A profile of the horizon plots the apparent elevation of the land-sky demarcation against the direction of view (the "azimuth"). In this plot the "adjusted altitude" measures the angle of view (shown as 1000 times its tangent). It was obtained from a DEM by first computing the viewshed for a 20 meter fire tower at a location near the middle: This ...


4

Viewshed analysis calculates the number of observers that can see a given location. No identification is given as which observers can see that location. The result is simply a single numeric value. If you have 10 viewpoints, then your resultant raster will have values in the range 0 - 10. Observer Points calculates visibility in the same way but the ...


4

I've used python scripts to run both the r.los and r.viewshed grass commands that Peter mentioned. The advantage with r.los is that it works straight out-of-the-box with grass6, but is slightly slower to run over large raster DEMs. r.viewshed is a bit of a pain to get running, but is a vast speed improvement on very large rasters. See if the times for ...


4

Set up your observer vector attribute table to contain the additional fields (RADIUS1, AZIMUTH1 etc). I haven't used viewshed in Arc for a while as I do it in other ways now but something at the back of my mind makes me think the field names might be case-sensitive (that might have been for the old ArcInfo 7.x on Unix though and might not apply to modern ...


3

The "Marmota" project at FBK, Trento, Italy, is offering the functionality you seem to aim for: http://tev.fbk.eu/marmota/ There are a series of publications available on that site. Furthermore, see the related question here.


3

You can make the preliminary tasks of your visibility analysis semi-automatic in few steps. Firstly, convert the shapefile of the observation points (Final_Branches.shp) in the CSV format, exporting only the coordinates: ogr2ogr -f CSV coords.csv Final_Branches.shp -sql "SELECT Easting, Northing FROM Final_Branches" The content of coords.csv should be: ...


3

For a ZTV you would not normally use the Observer Points tool unless you need to know which turbine is visible at a given location and you have less than 16 turbines. Use the Viewshed tool. The simple setup you need for the calculation is like this: OFFSETA = turbine tip height (or hub height if requested by client) OFFSETB = 1.65 (in your case, I often ...


3

Project your DEM and point file so that the map units are all in meters (to presumably match the z-values of the DEM). Alternatively, you can specify the Z_Factor to account for this, but for any surface analysis computation it is typically faster and more reliable if X, Y and Z units are all the same. The RADIUS2 is likely being read in as 1500 decimal ...


3

There is a freeware package called RadioMobile which is designed for radio communication studies that generates a view shed. The output is based on a DEM input and can be either a vector (point file) or Raster. I have been able to use the vector point file to create polygons through some scripting which I will be happy to share with you. Since you can set a ...


3

One of the activities (Activity 3) published recently by Esri discusses step by step details about locating a wildfire observation tower using freely available public data. Here is the Scribd Link For ready reference, the criteria they have used there: Within 100 meters of a roadway, for easy access Within 200 meters of a river, for access to water At ...


3

According to the licensing information, they probably share the same algorithms Licensing Information ArcGIS for Desktop Basic: Requires 3D Analyst or Spatial Analyst ArcGIS for Desktop Standard: Requires 3D Analyst or Spatial Analyst ArcGIS for Desktop Advanced: Requires 3D Analyst or Spatial Analyst And it can't be done without one of those two ...


3

See my answer to the question linked by PolyGeo. To get your points into ArcMap, export them as a CSV from Excel and then import that using Add XY Data. I'm sure you understand that you do not use this data to edit the DEM (I don't mean to patronise you and only mention this because of the way you phrased your comment, which rang an alarm bell - but maybe ...


2

Please have a look at Using Viewshed and Observer Points for visibility analysis In the lower part of the article you will see that there are several parameters that you can use. The parameter that you need are VERT1 & VERT2 To use these parameters in your ViewShed Analysis, your input point featureclass should have fields with these names. The ...


2

The inaccuracies introduced by ignoring buildings, trees, etc., suggest that we don't need extremely high accuracy in this computation. If we intend to exclude the cell on which the observer rests, along with immediately neighboring cells, then the calculations can be greatly simplified. This answer describes the simplified calculations. The view ...


2

There is no difference between Viewshed-3D and Viewshed-Spatial in terms of functionality. As per page 7 of the functionality matrix here: http://www.esri.com/library/brochures/pdfs/arcgis-server-functionality-matrix.pdf You can add extensions to ArcGIS Server Standard. You'd have to add one of those extensions to do Viewshed. EDIT: whoops... my answer was ...


2

Since high elevations are more likely to have large visible areas than low elevations, you could start with a suitability analysis that combines elevation and distance from existing tower(s) through a weighted linear combination (or similar). Once you can have a limited number of suggested locations, it's much simpler to run viewshed on those points and find ...


2

Avoiding python... You can create a very crude script in GRASS using a spreadsheet. In GRASS itself (not GRASS via QGIS) when you set up r.los (the line of sight analysis) it will generate code for the process at the bottom of the window, it will look like this: r.los input=dtm@LOS output=visible_area coordinate=XXXX,YYYY max_dist=15000 Copy this into a ...


2

If you perform an viewshed analysis it is important to pay attention to the x,y units and z units: If you work with a geographic coordinate system your x,y-units are degree. But (in your case) the z units are meters. If the x,y units and z units are in different units of measure, the z-factor must be set to the appropriate factor, or the results will be ...


2

OK, borrowing from the answer from @Jason, I was able to tweak it a bit to finally come up with a script that works great. I also switched it to use FID instead of OID. Either way, it will work. arcpy.MakeFeatureLayer_management (inPoints, "pts") with arcpy.da.SearchCursor('pts',['FID']) as cursor: for row in cursor: fid = str(row[0]) ### Must ...


2

In ArcGIS you can use the Viewshed tool (Spatial Analyst Tools > Surface). The Viewshed lets you calculate the surface locations visible to a set of points or lines (see the documentation).


1

Sequence of operations is: Start ArcMap Load raster Confirm that this definitely displaying in meters and is BNG Create your point, it looks as if you are displaying them as an XY event layer. When you create them make sure you set their projection as WGS84 (lat/long) as this it what they are They should automatically be re-projected on the fly because the ...


1

From http://resources.arcgis.com/en/help/main/10.1/index.html#//00q90000008n000000: SPOT The SPOT item is used to define the surface elevations for the observation points. Offset The offset is the vertical distance (in surface units) to be added to the z-value of a location on the surface. There are two offset items, one defining ...


1

ASCII is an inter-change text file format. ArcMap will behave better if you convert these inter-change files into ESRI grids then mosaic those as described above. You can make a simple model to batch convert all these ASCII files, this thread shows an example.


1

It looks like you're creating raster mosaic datasets. This will be ok for hill shades but I think you will have to creat a raster mosaic to create a viewshed over your entire project. A raster mosaic datasets is like an image catalog that references original files. A raster mosaic takes all source images and merges them into one complete image. The latter ...


1

It looks like you'll have to create a raster mosaic first. This will combine all of your input rasters into one dataset. To read up on mosaicking, see here. Once you have created the mosaic, rerun your viewshed. It should incorporate all of the raster areas.



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