Setting the z factor parameter correctly arcgis blog. How to create hillshade raster from srtm on arcgis 10. Dem or srtm data is a topography model with elevation information in it. Creating a hillshade from mosaic dem geonet, the esri. If the x,y units and z units are in the same units of measure, the z factor is 1. If the data is in a geographic coordinate system, change the z factor. If double clicking on the msp file does not start the service pack installation, you can start the service pack installation manually by using the following command. I am having problems creating a hillshade from a mosaic dem i made with 10m usgs seamless data dems. By placing an elevation raster on top of a hillshade raster and adjusting the transparency of the elevation raster, you can easily create a visually appealing relief map of a landscape. Right click on your hillshade layer and go to layer properties display and set transparency to 30%. This function uses the altitude and azimuth properties to specify the suns position.
Function to calculate hillshade for a digital elevation model. Hillshade coming out totally wrong geonet, the esri. The usgs shaded relief base map service from the national map was created with data from the 3d elevation program 3dep for large and medium scales 1. Generating a hillshade may take up to a minute depending on the size of your dem.
Create a hillshade raster of the base dem dem03, in this example using the spatial. Arcgis raster function service arcgis for developers. If the x, y, and zunits are all the same in feet, for example, the zfactor is 1. Creating a hillshade a hillshade is a shaded relief raster created by using an elevation raster and setting an illumination source typically the sun at a userspecified azimuth the angular direction of the illumination source, in positive. This zfactor adjustment method is cumbersome to implement with. The zfactor is a conversion factor that adjusts the units of measure for the. In this case changing the z factor to 2 will multiply the input dem by 2 before computing hillshade. Hillshade renderers can adjust a grayscale raster usually of terrain according to a hypothetical sun position azimuth and altitude. And then the default z factor value that it has of one. If the x,y units and z units are in the same units of measure, the zfactor is 1. Not setting the zfactor correctly makes the hillshades look heavy or leaden. University library, university of illinois at urbanachampaign. Change the altitude to 35 degrees, azimuth to 300 degrees and z factor of 1.
When working with data in geographic coordinates, this is a problem because the linear distance of a degree of latitude varies. Create a hillshade or slope using data in geographic coordinates summary. The hillshade raster will be automatically added to arcmap. I go to the spatial analyst tool hillshade and create the new hillshade layer, but the output is a grey screen in which you can view lines where the individual usgs dems boundaries were, not a hillshade. In this tutorial, we are going to learn about how to create hillshade raster from srtm on arcgis 10.
A hillshade is a grayscale 3d representation of the surface, with the suns relative position taken into account for shading the image. We can easily generate hillshade from srtm data in few clicks. The z factor is a scaling factor used to convert the elevation values. Also the hillshade itself does not look right, it appears very grainy and small. The zfactor parameter is in many spatial analyst and 3d analyst tools. The hillshade function produces a grayscale 3d representation of the terrain surface, with the suns relative position taken into account for shading the image. By default, a grayscale color ramp is used to display a hillshaded elevation model. Load the geotiff file into qgis raster load and rename the layer hillshade. Using the knowledge youve learned about arcgis, complete technical tasks such raster calculations and suitability analysis. The hillshade tool creates a shaded relief raster from a raster. This is designed to be used as a backdrop for topographical, soil, hydro, land cover, or other outdoor recreational maps.
Ensure the zfactor is 1 because our x,y and z values are all in meters. Some years ago i prepared a hillshade model for tanzania. Learn a new method for displaying hillshades and elevation. Dems for use in arcmap and other gis programs shows how to download. After the hillshade is created, open its layer properties dialogue. The hillshading is based on a solar altitude angle of 45 degrees, and solar aspect angle of 315 degrees. With a factor of 1 the default, a meter horizontal is the same as a meter vertical. Using arcmap or arccatalog your preference, load a base digital elevation model. Higher zvalues will result in a more exaggerated relief surface and, thus, in a more extreme shading. Individual dem quads were first converted to a common datum, and vertical unit, and subsequently mosaicked in arcgis 9. The hillshade for hawaii big island is in utm zone 5n, and the hillshades for the. Not setting the zfactor correctly makes the hillshades look heavy or. For example, if both elevation and dataset coordinates are meters and you want to exaggerate by a multiple of 10, the scaling factor would be the unit conversion factor 1.
Not setting the z factor correctly makes the hillshades look heavy or leaden. If you did not select a hillshade in the previous step, rightclick dem insert hillshade. When entering a file name for the output raster, the file extension determines what format the raster will be saved as. The z factor is varied based on scale so that a suitable hillshade is visible at all scales. Once that is all done, select an output path to save the generated hillshade and click ok. The scaleadjusted hillshade raster function template applies hillshading on the input elevation raster with a nonlinearly adjusted zfactor. The z values of the input surface are multiplied by the z factor when calculating the final output surface. The input dem is multiplied by the z factor before calculating shadows, so a zfactor of 2 will give shadows as if the mountains were twice as high.
The zfactor is a conversion factor that adjusts the units of measure for the vertical or elevation units when they are different from the horizontal coordinate x,y units of the input surface. Nonethis applies a linear adjustment by modifying the z factor according to the cell size, thereby accounting for altitude changes scale as the viewer zooms in and out. For another example, if your vertical zunits are feet and your horizontal x,y units are meters, you would use a zfactor of 0. For all the hillshades, the altitude was set at 45, the z factor at 1 and the output cell size at 10. In this article, we are going to focus on the hillshade. When performing a hillshade or slope function in arcgis, the z units are presumed to be the same as the horizontal x,y units. And what im going to do here is im going to rightclick on focal statistics and have it run that. We set the zfactor parameter based on latitude angular distance north or south of the equator. Scale and z factor have no effect on hillshade analysis in. If the vertical units are not corrected to the horizontal units, the results of. The z factor parameter is in many spatial analyst and 3d analyst tools.
Altitude angle above ground and angle directionaspect of lightsource can. How to create hillshade from dem on qgis gis tutorial. Derives slope and aspect in radias to calculate shading value between 0 and 255 using a given lighting angle and altitude. The surface area and ratio arcgis extension enables you to generate raster datasets of surface. Here, you can adjust the illumination with the altitude, azimuth, and zfactor through the. We can display this data in qgis in various mode such as hillshade, multiband, singleband etc. Add a point scene layer add an integrated mesh layer arcgis map image layer arcgis raster function service arcgis tiled layer arcgis vector tiled layer url blend renderer browse wfs layers change feature layer renderer change sublayer renderer colormap renderer control annotation sublayer visibility create a feature collection layer from a. The existing arcgis tools typically do not work well with data in a geographic coordinate system i. It is not uncommon to perceive the output from hillshade as looking peculiar if the. Focal statistics and the swiss hillshade spatial analyst.
The simplest and most interactive is to use the image analysis window. We set the z factor parameter based on latitude angular distance north or south of the equator. Displaying a dem with hillshadinghelp arcgis for desktop. Hillshade is a shaded relief from a surface layer considering the illumination source angle and shadows. Based on this other thread i used the equations to calculate for my area. A tinted hillshade is a combination of a hillshade applied to the terrain, fused to a colormap applied to the same terrain to represent elevation. It is a qualitative method for visualizing topography.
Then i open the dem terrain models dialog and select this raster layer, choose an output file and fill in values for scale and z. This article points to a file gallery where the files are available for download. It was fun and before i knew it i had prepared elevation models for seven more countries. Hillshade output example using hillshade for display.
Using arcmap hillshade command to simulate 3 dimensional images. Click customize toolbars spatial analyst on the main menu. Activity constant to store a zfactor conversion constant applied to the hillshade. In the symbology panel, next to render type, choose hillshade. Home creating 3d visualizations in arcmap using hillshade. The zfactor adjusts the units of measure for the z units when they are different from the x,y units of the input surface. The hillshade were created from these dems using the hillshade function in arcgis 9. We need to enter a scale correction factor of 111120 in the scale ratio vert. If you add appropriate or correct zfactor to your dem while creating hillshade, you can avoid too much contrast in the hillshade and too much bumpy in the flat areas.
The hillshade result is scaled dynamically by adjusting the z factor using one of two options. Hillshading is a technique for visualizing terrain determined by a light source and the slope and aspect of the elevation surface. The z factor adjusts the units of measure for the z units when they are different from the x,y units of the input surface. The spatial analyst toolbar is added to your arcmap session. When the dem or srtm data is rendered using hillshade, we will get the following. And if you increase the z factor, youll essentially be creating a display that exaggerates the heights of the surface. This value is often overlooked, but it is important to consider when creating a hillshade, because it has a significant impact on the appearance of the output. This map portrays elevation as an artistic hillshade. It is the number of ground x,y units in one surface z unit. If your xy units are in meters and z units are in feet, the zfactor would be 0. Also, changing the settings for scale and zfactor does not have any effect on the resultant hillshade. Arcgis has many useful tools for calculating slope, aspect, hillshade and curvature from dem rasters.
The zvalues of the input surface are multiplied by the zfactor when calculating the final output surface. I used an srtm dem to create a hillshade in qgis 2. However, the resultant hillshade seems to be vertically exaggerated. To apply vertical exaggeration, you must multiply the conversion factor by the exaggeration factor. Right click the layer to open the layer properties window. This extension offers some advantages over these existing tools in that. The z factor is used to exagerate or reduce the altitude effect. I feel like it has something to do with the zfactor field in the hillshade dialog, but i have no idea what to set that to so i leave it as the default value of 1. Light characteristics, verticalgeographical source will be determinant for the hillshade. You can either make a temporary hillshade for display only or you can make the output permanent for use in the future.
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