Questions tagged [contour]

Contour maps depict spatially-varying values, such as elevation, by means of curves of equal value.

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3
votes
1answer
205 views

Selecting contour lines with higher elevations on either side

I want to select contour lines that have lower elevation values from neighboring contour lines. I'm using ArcGIS but do not have the hydrology tool set. I can use open source if needed. I thought ...
1
vote
1answer
258 views

Generating seamless contours across tiles from TIN/LiDAR data?

I have both TINs and LiDAR data for an entire county, divided into a grid of multiple tiles. I want to generate contours from this data at 2 foot intervals, using ArcGIS 10.5. I decided to do this ...
1
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0answers
161 views

Solutions for generating grade/slope estimate heatmaps from a topography contour layer

Given a shapefile layer of 5-ft interval topography contour lines overlaid on google earth, I could, using the Ruler tool and some simple arithmetic, calculate average percentage grade numbers for a ...
4
votes
3answers
607 views

Extracting contour lines from ortophoto map

I am quite new to QGIS and need some help with this. Basically I have the coordinates of a piece of land which I can find both through Google Earth and my country's mapping service website. I ...
2
votes
1answer
75 views

Jagged edge of circle

I am using LiDAR data to locate Sinkholes(depressions) in an area. I am doing this by making the contours and checking the contours(if they are circular enough or not, elongatedness, etc.). But I have ...
1
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0answers
253 views

QGIS isolines from points and lines

I'm getting started with QGIS and I want to use survey data to generate isolines. Contour plugin works well except when surveyed area has linear details (say, a road) that are elevated relative to the ...
2
votes
0answers
1k views

Smoothing the contour line in Python?

I used the NCEP 2.5 degree*2.5 degree data to plot the 850 mb wind field and heights. But, I didn't know how to smooth the contour line. Scipy.ndimage.zoom didn't work well and some details are missed....
8
votes
1answer
1k views

Accurately interpolating elevation from contour lines in QGIS?

I’m trying to interpolate elevations from contour lines (~70000 at 1m intervals, spanning ~20km^2) in QGIS.  When I interpolate using Inverse Distance Weighting (IDW) in the Interpolation plugin it ...
0
votes
1answer
232 views

Creating flowline by connecting points in ArcGIS Desktop?

I have a dataset that contains X,Y coordinates of a glacier and the surface elevation is plotted as a Z-coordinate (see attachment). What I want to do is connect the top with the bottom of the ...
1
vote
1answer
633 views

Error with contour plug in (QGIS 2.18.4)

I am trying to use the contour plugin in QGIS 2.18.4 Las Palmas on Windows 10 (both are 64bit). When I choose the layer I want to use there is not problem. However when I select the field, I receive ...
1
vote
1answer
346 views

Using contour tool in QGIS?

I have a point layer with meteo-stations data. When I tried to obtain filled contours with contour plug-in it seem ok, but when I tried to work with that layer happened a mistake and I don't know how ...
0
votes
1answer
173 views

Finding highest path of DEM or contours file within area using ArcGIS Desktop?

I would like to create a polyline from one specified point to a target point. In between, I'd like to the vertices to fall on the highest point of elevation of that Y coordinate. Essentially, this ...
3
votes
1answer
632 views

Finding “negative contours” when making contour lines from DEM

I have a large 2m DEM which consists mostly of mountains. But here and there there are depressions in the terrain which I need to find, or even better, automatically find in contour lines I'm planning ...
1
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0answers
118 views

How to use QGIS to create GeoTIFF contour map to import into Mapbox? [closed]

The final product I'm trying to achieve is a Mapbox interactive map with a colored contour layer. I have a CSV file that contains rows with "LATITUDE,LONGITUDE,VALUE" in a 0.01-degree grid. I want ...
1
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0answers
72 views

Problem with contour line

I have a problem when I create a contour line from DEM, it's become sharp and not correct ( image attached ) . DEM cell size = 5m Contour interval = 5m
0
votes
1answer
160 views

Seeking DEM data to make hillshade and contours?

I used to make hillshade and contours for several scales from Aster 30m GDEM with ErMapper. My data is not covering everything I need, so I am looking for a recent one. I saw there was a Aster GDEM ...
1
vote
1answer
73 views

Altering existing polyline shapefile that displays contour lines using ArcGIS Desktop?

I have a polyline shapefile that displays contour lines. It has contour lines that have a interval of 10 m. Is there any way to change the interval to 500 m in ArcGIS?
1
vote
0answers
90 views

How to align 3D contour file, aerial imagery and design drawings from engineers in microstation v8i series 3.

I am looking to align a 3D contour dgn file with the design drawings from an engineer in microstation. Then align an orthorectified aerial image (Scale 1:10 000) to the contour file and design ...
5
votes
4answers
693 views

Computing pole of inaccessibility

We are interested at the "Pole of inaccessibility" (https://en.wikipedia.org/wiki/Pole_of_inaccessibility) of our country. Our approach is to use QGIS, and download coastline ([ngdc.noaa.gov]), and ...
5
votes
1answer
600 views

How to find depressions (sinks) and hills based on contour line features

I have contour lines (interval 0.1m), derived from a DEM (1m). I used the thinning ratio to find only features, which are like circles. I've imported these features into a Spatialite database. The ...
0
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2answers
105 views

Seeking contour data for Oregon? [closed]

Does anyone know where I can find good contour layers for Oregon? I do not have spatial analyst, so I can not make my own.
-1
votes
1answer
70 views

Automating contour selection

I'm working with a lot of vector contour data, and it's getting annoying just selecting by Z-Value. Is there a tool/ model/ script that I can just enter my starting elevation and contour intervals ...
2
votes
0answers
36 views

Why are there null geometry lines after using the contour tool in Spatial Analyst?

A few months ago, I ran the Contour tool on two separate DEMs (one was smoothed and the other wasn't). The contour interval was set to 1m. Today, I noticed that there were several features created ...
1
vote
1answer
387 views

Watershed analysis using GRASS GIS

I have Contour lines shapefile which I imported that into GRASS and converted to a DEM using the IDW interpolation technique (r.surf.idw with npoints 250). Now I want watershed analysis to be done ...
0
votes
1answer
181 views

Extracting raster information within/inside polygon (for each contour)

I have raster data of NDVI and DEM I have already created contour from DEM. Now I'm trying to find following: for each contour find the raster information within the contour. Can anyone suggest ...
2
votes
1answer
92 views

Contour vs elevation semantics

I accept I am being a pedant here, but feel the semantics are important.. If I were to drawn a path representing a 'route' between 3 random points on the earth's surface, then establish the nearest ...
2
votes
0answers
346 views

Extracting xyz data from .dxf after conversion to shapefile in QGIS

I have both a .dwg and derived .dxf data set originally generated in AutoCAD Civil 3D. It appears as a series of triangles which cannot be exploded but each individual triangle does have xyz ...
0
votes
1answer
91 views

DEM showing areas in the ocean to be greater than 0m (my MSL in my project)

I am a new GIS student currently working on a coastal flood model in arc map, where I intend to create flood polygons at various heights above 0m contour (MSL)to represent the extent of area flooded ...
0
votes
2answers
561 views

Fixing contour lines in ArcGIS for Desktop?

I am using ArcGIS for Desktop and I want the lines to be curvy not that straight as the picture depicts: solution: In Arcgis , the smooth lines tool , peak ...
0
votes
1answer
127 views

Area of contours, broken lines

I have flown topo lines covering a large AOI. Some of these lines stretch across the whole area and therefore aren't closed while others just cut off and also aren't closed. I want to calculate the ...
0
votes
2answers
640 views

1ft contour shapefile displaying in meters

I generated a shapefile that has 1ft contours. It works great when imported to QGIS except the elevation labels are displayed in meters instead of feet. I've found two places to select feet as the ...
1
vote
1answer
118 views

Sample point elevation from a given contour

I need to sample the elevation at number of predefined location given in CSV format (but could convert to shapefile if needed). My input data is a shapefile of contour lines. Is it possible to sample ...
0
votes
1answer
430 views

Ready made Contours from SRTM data?

I need to create a map with SRTM data but use contours instead of the grid data. I can use ESRI software to create contours but they aren't the nicest looking, mostly in flat areas. Does a good ...
2
votes
1answer
167 views

Are there any tools that can identify ravines/steep elevation drops from contour line data?

I am trying to create polygons around rivers that extend all the way up to the top of the surrounding slopes. I am currently able to do this using stream data and contour data, but I would have to ...
1
vote
2answers
537 views

Extract elevation data from contour lines

I am working with QGIS. I used raster-extract-contour to get contour lines from a raster image. Now I want to break up my single vector file into multiple layers based on elevation. How do I do this?
6
votes
2answers
2k views

How to replace pixel values in a single band DEM?

I have a single band DEM as a GeoTiff. I would like to replace values above or below a certain threshold with 0. Can I do that with GDAL?
2
votes
2answers
2k views

Leaflet filled contour map

I have evaluated the Getis-Ord Gi*-spatial statistic for each point in my map. Like this, each point is assigned a Gi-score and due to this a certain color, as you can see in the image below. What I ...
4
votes
3answers
2k views

Exporting contour lines from CAD to GIS

I've been using GIS softwares in the past few years by I'm new using AutoCAD. Well, I have contour lines in AutoCAD and I want to export it into QGIS (I also have access to ArcMAP). I saved as .dxf ...
1
vote
1answer
507 views

Generating Contours from csv Concentrations

I have a shp file showing locations of various wells on a site. I have linked (joined) a csv file of analytical results to this file. I am now looking for a method to generate contours based upon ...
8
votes
1answer
155 views

Why is the “Contour” tool returning contours with an odd rectangular pattern?

I am generating 2' contours made from a smoothed DEM that is 3.2808 foot (1m) horizontal resolution. The result shows these odd squares that are about 80' on a side. The smoothing was done using 8 ...
5
votes
2answers
9k views

How to perform a slope analysis in QGIS? [duplicate]

I have contour information in the form of line features (see picture below) and I want to do a slope analysis in QGIS. Is it possible?
1
vote
0answers
15 views

Any way to remove 2 point polylines in bulk?

QGIS: I have successfully created contours from a DEM and subsequently cleaned them up using generalizer tools in the following order: 1. Vertex reduction 2. McMinimans distance algorithm. The ...
12
votes
2answers
9k views

Convert raster to smooth contour polygons in QGIS

I have had limited success creating smooth contour polygons from a raster layers. I have created contour lines and boundary polylines and then used QGIS Union. Then I use QGIS Polygonize. Then ...
1
vote
1answer
1k views

Grid thematic map in Mapinfo

I have a tab file with the contour lines for an area, and also a tab file with the land polygon. Now, I'm following a tutorial written by a colleague a couple years ago, where a thematic map is ...
-3
votes
1answer
134 views

Help with definition query [closed]

I have a layer of 5ft contour lines, and it includes a field called "Elevation" that has the elevation of that particular line in feet, (ex: 1555, 1560, 1565 etc.). I want to only show lines for every ...
1
vote
0answers
37 views

Converting Labels to Annotations moves position of labels

Why are my contour line labels moving after I convert them to annotations? I am using Maplex to place them. But if they still move after I converte them to annotations, the whole maplex placing ...
3
votes
1answer
226 views

How to fix label contour lines layer displays on top of all layers in QGIS

How can I fix the situation, when the label contour lines displays (on top of all layers) on top of this layer? QGIS 2.15.0-Master
0
votes
1answer
57 views

Converting polygons to contours based on value in polygon table

I have the following data and have been asked to create a map that shows the same data set but displayed as contours. Each polygon has a value in it's table called "count". The "count" field is ...
2
votes
1answer
564 views

How to calculate mean elevation in a DEM between a specific interval?

I have a DEM with different elevations between 100 m & 3828 m. I just want to calculate mean elevation higher than 1500 m? Can I do that?
3
votes
1answer
147 views

Scripts to automate conversion from DEM to contour shape files

I am using the DEM files in the Cornell CUGIR repository to build contour layers in QGIS. The problem I have is that while it is easy to do, it requires many manual steps in QGIS that are both ...