Mar 05, 2020 converting raster surfaces to contour lines. Can contours be digitized automatically from topographic sheets. Alantoms hello, i need some help making contour lines more visually appealing and easier to read what is going on. Contour maps graphically illustrate elevation changes in an. This arcgis modelbuilder model generates smooth contours with a nice cartographic appearance and automatically calculates index contours at 50 and 100. The contour function generates contour lines by joining points with the same. Aug 02, 2012 since this is for displaying data, and not analyzing the data, the smooth tool would give visually good results.
It utilizes arcgis geoprocessing tools and requires the spatial analyst extension. Under name type elevation, and under type select text numeric fields also work but text fields seem to be less problematic. The resulting line passes through the vertices of the input line. Increment at 100 and kept the minimum number of points for a contour line above 300. Smoothing a feature smooth you can smooth a feature by using the smooth command on the advanced editing toolbar or the smooth line geoprocessing tool or smooth polygon geoprocessing tool. Help to simplify or smooth contours geonet, the esri. In the 2007 product, sanborn applied minimal smoothing routines to minimize any distortion. If this field does not exist, click options add field.
Smooths sharp angles in lines to improve aesthetic or cartographic quality. A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness of slopes. We have 1ft contours derived from lidar flown a few years ago. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value. It calculates a smoothed line that will not pass through the input line vertices. If you do, it will be so, so nice to share it i am not a programmer, but do need such a script to use it with arcgis 10. To create a smooth contour set for topography and other grids, it is helpful and relevant to slightly smooth the data before contouring. I am trying to get nice smooth contours using arcgis. The usgs national map viewer uses a cart checkout system to download its data. I was just curious on the steps involved in extracting contours from a topo map without digitizing them, delineating the contours from all the other vector features after raster to vector conversion, and then the creation of a dem. Exporting contours from arcmap to autocad map and data library.
In flat areas, contour lines can be very linear and angular. To create contours in a different unit than that of the zvalues, set an appropriate value for the zfactor. Paek acronym for polynomial approximation with exponential kernel. Jagged overlapping contour lines instead of smooth natural. The national map download client allows free downloads of public domain contour data in either esri file geodatabase or shapefile formats. I am getting something like on image 01 and i want to get a smooth poly line image 02, i know it will create more points. Struggling with smoothing contour lines geonet, the esri. Contour lines are often represented by many individual line features in a geographic information system gis, which can result in many more labels being placed than necessary. For reference, here is the merged dem raster and my contour results trying different settings. You can use the following geoprocessing tools to create contours from a surface. How to generate contours in arc gis smooth and rough contour.
Producing cartographic contours from elevation models in. With the default value of 1, the contours will be in the same units as the zvalues of the input raster. The polynomial approximation with exponential kernel paek method paek in python smooths lines based on a smoothing tolerance. The most efficient way of doing this in arcgis is by using the focal statistics tool in the spatial analyst toolbox.
In essence, the less smooth the contour, the more accurate it depicts the terrain. Set the map scale parameter to the scale at which your cartographic products will be printed. Visually inspect the map to verify the distance between contour lines the contour lines is more like figure 2a than figure 2b. Inputs containing features that will act as barriers for smoothing. Creating smooth contour and labeling on arc gis youtube. Arc info lattice files were then created using thegridlattice command and a lowpass filter was run on them to smooth the data. This model removes some manual steps to create contours and results in contours that often look very close to usgs topo maps. Create contours by executing the spatial analyst contour tool. I have just loaded up the srtm v3 for your geographic location and generated 0. When contour type is set to contour smooth only, the input elevation layer is. Click on the download data arrow near the top of your screen.
Creating contours from dem files in arcgis arcmap or arcscene in arcmap. The problem is that they are extremely bendy and the smaller the scale the more difficult it is to see what is going on. Contour coverages were created from the lattice files using a contour interval of 30 feet, which was consistent with the input scale of the data. Create contour lines with point or line shapefiles. Apr 07, 2011 1 thought on generate smooth contours from dem arcgis, modelbuilder veni january 4, 2012 at 8. If the output is a shapefile, the bezier curves will be approximated, since true bezier curves cannot be storied in shapefiles. To smooth multiple lines, use the geoprocessing tools. A contour is a line through all contiguous points with equal height or other values. The contour lines are generated based on the zvalues in the input raster, which are often measured in units of meters or feet. Following smoothing, contour lines were generated at 10meter intervals from 10 m to 100 m and at 50meter intervals from 100 m to 400 m.
The image of contour lines on the left a is a desirable outcome where the closest contour lines are a little over a millimeter apart. Contour lines look blocky, appearing to trace raster cell boundaries description. The appropriate method for generating smooth datadriven contour lines is by smoothing the input dem using the focal statistics tool in arcgis. In arcmap or arcscene, click the 3d analyst menu on the toolbar, point to surface analysis, and click contour. This tutorial assumes that the elevation data either as points. You can create contour lines for a raster, triangulated irregular network tin, or terrain dataset surface. To generate contours, a smooth arithmetic mean convolution function that assigns a weight of oneninth to each cell in a 3pixel by 3pixel matrix was applied iteratively to the bathymetry ten times. Creating contours using arcmaparcscene map and data library. The following steps describe the smooth command, which smooths only one selected line. In order to monitor the level of smoothness of a dem, creating contours can be helpful. Create contour lines with point or line shapefiles arcgis makes generating contour lines from elevation data simple. Generate smooth contours from dem arcgis, modelbuilder.
The latticeoperate command was used to convert from meters into feet. Creating contours from dem files in arcgis arcmap or. The contour tool creates contour lines connecting the same level of elevation. To get elevation data for arcgis, check the box to the left of. The input raster data source was the arc second version of the ned. Contours are quickly and dynamically generated on very large datasets, such as the world elevation.
Before exploring the raster data in 3d, we need to smooth the elevation model, so the 3d model of campus fits the elevation model nicely. Hi guys, just wondering if there is a plugin extension which will smooth all contour lines i have got from slicing terrain with planes. Gis data list use if data not available in gisopendata portal above. The raster values are integers, which align with the contour. How to derive contour lines from a surface deriving contours. To obtain smoother lines although less accurate, we will use the smooth line tool available in. Due to the input raster field size, the contour line result will have a tough appearance with squares.
How to generate contours in arcgis for desktop md imap. Click on the plusminus signs to expandcollapse the different categories. Since they are 1214, my goal is to get the arcmap file dialed in with nice smooth contours can work with them to customize if needed, export it to. Calculate contour fields that pertain to defense mapping data models. After having created a dem file, the file can be used to create contours. If you are given two or more files to download, go back to your map and make sure ned. Set the contour interval to match your target value and use the zfactor to adjust the. The image on the right b is too dense with many of the contour lines. Contours can be smoothed to provide a more cartographic. Specify the location and name of the generated layer. I set the parameters in various ways but for the most part i left the max contour level at 10,000. This is not a bug, it is exact contouring of the data.
Do you have a python code for a script smoothing vector contours with bspline. The elevation data is typically in the form of points collected by either total station, level, digital theodolite, or some other type of surveying instrument. The contours are isolines created as rasters for visualization. The gradient of the function is always perpendicular to the contour lines. You must first ensure that the spatial analyst menu is showing on the. Showing dem in 3d view in arcgis dem in 3d view in arcmap dem in arcsene duration. The current result looks like this, which is way too pixely whenever the line is not straight. Contour type is used to produce either contour lines or polygons. In order to create smooth contour lines, we first need to smooth our dem to ensure the vector output is datadriven. Lidar light detection and ranging is an optical remotesensing technique that uses laser light to sample the earths surface and produce highly accurate x,y,z measurements. These packages include printed topographic map series, gps basemaps and comprehensive. The contour interval of a contour map is the difference in elevation between successive contour lines. Overall, the 2007 contour dataset is a better source to use given it was produced using more current techniques and minimal smoothing.
How to generate contours in arcgis for desktop youtube. To improve the appearance of contour lines, use the focal statistics tool to resample out the dem. The following key features make this function powerful. If you uncheck smooth contour lines areas to improve appearance the contours will not overlap.
To create a smooth contour set for topography and other. These contour datasets were generated from the national elevation dataset ned and the national hydrography dataset nhd in a fully automated process. Smooth contours by applying a defense mapping specific algorithm. I have already smoothed out the dem using focal statistics, simplified and smoothed the contours. Occasionally, contours may be created that have square or blocky outlines, appearing to follow raster cell boundaries. Now that you have a smoothed raster layer representing a dem or dsm, you can convert this to contour lines using the contour tool. Contour lines look blocky, appearing to trace raster. Each smoothed line may have more vertices than its source line.
Click the dropdown arrow and click the surface from which you want to derive contours. Large scale contour intervals are variable across the united states depending on complexity of topography, and as contours are generated per us topo quadrangle, lines may not match across quad boundaries. Home creating contours from lidar data using arcgis. If smooth contour lines are the desired final product, we must generate. Users are encouraged to use our cloud based open data portal, geohub, to download data in various formats. To avoid this problem, line features that represent contours can be treated as special types of line features.
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