Tag Info

Hot answers tagged

17

Using ST_Azimuth Planar bearing can be calculated using ST_Azimuth: SELECT ST_Azimuth(ST_MakePoint(1,2), ST_MakePoint(3,4))/(2*pi())*360 as degAz, ST_Azimuth(ST_MakePoint(3,4), ST_MakePoint(1,2))/(2*pi())*360 As degAzrev degaz degazrev ------ --------- 45 225 For spherical azimuth (Quoting potgis-users group): ...


12

Have you looked at a globe lately? :) The prime meridian divides the earth into the western and eastern hemispheres. "West Antarctica" is in the western hemisphere, hence the name.


10

You should be able to use the Arrow At End symbol from the Symbol Selector to show the digitised direction of polylines.


10

For anyone coming across this question now - PostGIS supports ST_Azimuth on geography (spheroid) as of 2.0.0.


5

The Weather Underground does this - Road Trip Planner (with Weather) http://www.wunderground.com/roadtrip/ Example Route above: ...


5

Since you mentioned that are you doing network analysis, I recommend assigning the symbology for your road edges within the network dataset layer in the TOC instead. You are on ArcGIS 10.2, so here are the steps: Add the network dataset into the ArcMap TOC. Open the Layer Properties dialog box by double-clicking the network dataset layer in the ArcMap ...


4

Line data (of any format, be it GIS/CAD/etc.) typically defaults to the 'direction' of the line being based on start point or first coordinate given to end point or last coordinate given. Direction of travel is therefore considered in terms of with or against the direction of the line. The most common scheme (there can be others) for attributing this in a ...


4

first create the aspect raster with r.slope.aspect then display the arrows with d.rast.arrow.


4

You could try this in two different ways, either rotating your symbology (mark each location with a symbol that points at ), or rotating a label (each location has a static point symbol, and label rotated). Here's the Esri help page for each method: Rotate the label: Setting label rotation using a numeric field. I think this would work better for your ...


3

Not exactly an answer, but have you seen The Open Source Routing Machine (OSRM) Their routing engine works on OSM-data it seems, but it is opensource, so it could provide som pointers. And their implementation is FAST: http://map.project-osrm.org/


3

Add an overlapping Marker Symbol line and make the Template as shown. For the marker symbol I used the Dimension Style set Solid Triangle 2 which points to the right. I resized it down from 18 points to 12 points. Now I have a question for you. For the line ends marker I tried using the dual arrows and a green circle with a dot like you showed, but the ...


3

For MapInfo there is a tool called Rotate Symbols under the Tools menu. This will allow you to rotate symbols based on a fixed value or an attribute value in a specific column. There is a tutorial available here with detailed instructions. Within ArcMap this can be done on the symbology tab of the point layer properties, using Rotation under the Advanced ...


2

The ArcMap Path Distance tools can do this, although it's moderately complex. Specifically, you need to use the horizontal and vertical factors. This looks at the aspect/elevation to figure out whether it's going uphill, downhill, or parallel to the slope, and assigns a different weight to each direction of approach.


2

A) Direction is calculated from the difference between start and end point B) Distance of line is best to be calculated simpy by $length and is the sum of all individual parts Also note nhopton's comment on how to get bearing of each individual segment: A most elegant solution, thanks. I'd mention that if you need to determine the bearing for each ...


2

Assuming you just want the general orientation of the polygon, rather than a specific segment... try the Minimum Bounding Geometry (Data Management) ArcGIS tool with the RECTANGLE_BY_WIDTH or RECTANGLE_BY_AREA geometry type and the MBG_FIELDS option. The MBG_FIELDS option will add the following fields to the output attribute table: MBG_Width—The ...


2

I'm going to suggest an alternative approach here that should get you what you want and still leave the data in a conventional format. As I pointed out in my comments on your other question, if you change the actual one-way attribute you will cause problems using network analysis software and confuse others working with the data because you won't be ...


2

You can edit the style of your output line layer (Layer Properties > Style) and change the Symbol layer type from "Simple line" to "Marker line" to automatically add more symbol layers: You can choose the shapes you want the line to consist of (in this case, arrows) along with other options such as intervals, widths and angles of the symbol. Hope this ...


2

With ArcGIS for Desktop Advanced, you could Convert all depression lines vertices to points (with Feature Vertices to Points) Convert all vertices back to lines (with Points to Line, with the Close Line option checked) Revert the direction of all lines (with Flip Line).


2

When considering turns as features in a network dataset, they must be modeled first. That means you have to create an actual turns feature class that has its own geometry to be traversed. When turns are not specifically modeled (ie, the Global Turns properties you mention) they aren't features that are traversed, just analysis variable properties, which is ...


2

Use the GeoServer SQL view feature, and SQL's ST_Project like, SELECT id, ST_SetSRID(ST_MakeLine( ST_MakePoint(lon,lat), ST_Project( ST_SetSRID(ST_MakePoint(lon,lat),4326)::geography, distance, pi()*azimuth/180.0)::geometry ),4326) AS geom FROM mytable; If you have long lines and want to plot them as great circles on a ...


1

Relative to another point, and assuming a north-oriented map: If the longitude is less, it is to the left, if more, to the right. If the latitude is greater, it's above it, if less, below it. Based on the North-clockwise bearings in the first link, 0 is up, between 0 and 90 (exclusive) up-right, 90 right, > 90 - < 180 down-right, 180 down, > 180 - ...


1

I may have a solution for you. If flow in one direction is consistently lower than in the other direction, this would work. I think you have much of the answer included in the question. I would attempt to duplicate the layer and draw the limited flow on top of the greater flow and have them both symbolized by the flow value.


1

Have you followed the instructions in the tool's help file? If the tool is grayed out, then you probably have not taken the first two critical steps. First, you must start an edit session. If your new points should be in the same database/file, then Editor > Start Editing will suffice. Otherwise you need to create a new database/file to hold your new ...


1

Since you only have 5 points, the following won't take too long. Make sure your layer is editable. In the Construction Tools in the create features dialog, select "Point at end of line" Begin drawing a line from one of you points by clicking on the point. Right click and choose Direction/Length and enter the details. Repeat for the remaining four ...


1

The answer depends on what "field length" means. Suppose the length is the longest segment, oriented with the wind, that is contained within the field. First rotate the data so that the wind direction now appears horizontal (west to east), then apply any of the solutions to this problem for the special case posted at How to calculate the maximum distance ...


1

I apologize that I can't answer how to do it with arcgis but I made a successful test with Spatialite-gui. I created first a new Spatialite database and imported some road data from a shapefile. Then I executed these three SQL commands: alter table roads add column from_or_to; update roads set from_or_to='F' where MbrMaxY(EndPoint(geometry)) > ...


1

There are 2 possibilities, what could be wrong. (1) You missed to make use of one-way street information as Uffe answered already. In pgRouting this means, that you need to use reverse_cost and then have different cost values for each direction. See the documentation of Dijkstra algorithm for example, and especially look at the "with reverse_cost" example. ...


1

It seems that all the values in slopes are rounded to the nearest 0,5. So 0,401 m / 2.8284 m = 0,14177, would instead be 0,5/3 = 16,6667. Or if distance is 2 metres, then 0,5/2 = 25 %. In the manual it says the values are rounded in FLAT areas, which seems to be a little off considering it does that where slope is 25 %. Another remark is that in flat areas ...


1

If you are using ArcMap and representing the sewer network using line features go into the layers properties, change the line type to cartographic line symbol. From there you will want to select the line properties tab. In this window you should see a box named Line Decorations with 4 radial buttons. Select the choice that you need. Once you have done so ...


1

I would run they each of the individual segments and for each find the matching node in the complex polyline for the start as well as the end node of the section. Now you can check if the end node number is larger than the start node number. If so the line direction of the section is the same as the direction of the polyline. If not, the direction is ...



Only top voted, non community-wiki answers of a minimum length are eligible