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25

Nutshell Each set of 3 images below should be read such as "grey (band) + opacity (band) = transparent result". You can test these processes within minutes via the associated github hosted makefile. Process #3 is the one which I recommend, with a threshold between 170 (keeps strong shadows) and 220 (keeps all shadows). Process 3 provides the strongest ...


17

Use Bilinear Interpolation resampling during display You can somewhat improve the display by changing the resampling method used from the default Nearest Neighbor to Bilinear Interpolation. Layer Properties -> Display Tab -> Resample during display using: Bilinear Interpolation. This effect works best with DEM and the default black and white color ramp. ...


16

The proper name for those old-style shaded relief maps is "Hachure maps". I agree that they do look very pretty, even if they are less useful for actually conveying elevation than contour maps. According to that Wikipedia page, the rules for drawing Hachures are as follows: The hachures are drawn in the direction of the steepest gradient. The ...


9

Arcmap's on the fly hillshade, the method described, is quick and dirty and was never meant to replace the hillshade result from Spatial Analyst and/or 3D Analyst. Although the same term is used to describe both they are not the same at all. To create a true hillshade without Spatial Analyst you might try GDAL's gdaldem: gdaldem hillshade dem.tif shade.tif ...


9

I usually post-process a copy of the raw hillshade in some external graphics editing program that I can directly over-write (save, instead of save-as) Photoshop and GIMP are two that come too mind. The process in a nutshell I follow: Import GeoTiff'd Hillshade -> Tone -> Median -> Reduce Noise -> Gaussian Blur Your geotiff should be accompanied with a ...


9

The linked source mention "change its fusion mode to < Multiply >", so the operation to do is not a simple average of input hillshades (for this, see also How to average gdal_hillshades?). It's something else. Yet, let's create the 3 different-sunlight-directions hillshades : gdaldem hillshade input.tif hillshades_A.tmp.tif -s 111120 -z 5 -az 315 -alt 60 ...


8

This doesn't help with your goal unless you're willing to do some coding, but Michal Migurski recently did some experiments in automating hachures, which were built on by Eric Fischer.


7

Yes, it can. Phong shading is a sum of ambient, diffuse, and (specularly) reflected light. The ambient portion is represented by the usual map of the DEM. The diffuse portion is computed with a hillshade. A "hillshaded DEM" is a weighted sum of ambient and diffuse reflections. The formula for the reflected part of the image can be computed in terms of ...


7

For relief shading in GRASS, better use r.shaded.relief. It comes by default with light from west to east. Like this (SRTM example): For my perception the valley looks ok in this example. The colortable comes from r.colors (there are "terrain" and "srtm", see here for examples of these color tables).


6

If you are looking for a good looking hillshade that takes some time to create, but is great for larger projects where it will get a lot of exposure, you might try the Swiss Hillshade Method - it requires 3 layers, but you can then export them to one georeferenced tiff to save space and for portability. This method DOES require Spatial Analyst, I believe, so ...


6

Since hillshade is just an overlay, you can do it anyway that gives you the desired result. However, the usual way to emphasise the terrain is to apply a vertical exaggeration. In ArcGIS you use the 'Z-factor' in the hillshade tool to do this as per the documentation here. You multiply the z conversion factor by the exageration factor. If your z-units are ...


6

A few thoughts: A previous answer correctly recommends resampling during display to smooth out the irregularities in the hillshade. This is primarily used for cartographic effect when you are finishing a map. Use the Image Analysis window to run a 5x5 smoothing window over the image Find better elevation data. 10 m NED Data is available for the ...


5

Which hillshade module, Martin? In QGIS Master there are two under the Raster menu: Raster -> Terrain analysis -> Hillshade and Raster -> Analysis -> DEM(Terrain models) If you haven't already done so, I should try the second one (set 'Mode' to 'Hillshade'). Also, tick the 'Creation Options' box and enter 'TFW' under 'Name' and 'YES' under 'Value'. Doing ...


5

If your DHM is a ESRI ASCII grid file, you should definitly give Dr. Jennys Terrain Sculptor a try: http://terraincartography.com/terrainsculptor/! Look also at this post for converting to ESRI ascii grid: http://freegeographytools.com/2010/converting-dem-files-to-asc-format-for-terrain-bender-creating-matching-raster-overlays


5

There's nothing wrong with this hillshading and the coloring certainly is not the problem. We are experiencing a common, well-known phenomenon: our visual processing inverts depth and height when the terrain appears to be illuminated from below. (Look at the image again while standing on your head: it will appear correct.) That's why it's best to place ...


5

It's possible. From the ArcGIS Resource Centre blog by rajnagi: An alternative to overlaying tints on hillshades. This involves several steps, first of being to convert the DEM to an RGB based raster. This is done by "exporting" the raster to a new dataset after you've applied the desired colour ramp. I'm posting the article contents below as sometimes ...


4

When you say in item #2 "can I create my effect with creating a Hillshade layer (without using Spatial Analyst)", do you mean alternate applications for creating a hillshade? If you want to use an application outside of Spatial Analyst, I just recently learned about (but never have used) the "SEXTANTE for ArcGIS extension" (free), which allows users to ...


4

I have always been instructed to increase the z exageration when doing hillshade. I just tried 100 on mine and it seems a bit extreme. Also changing the stretch type makes a big difference in the look of hillshade. Since you are talking about how it looks you might also look at this help item. esir help Which says that hillshading iis applied at the display ...


4

I'm not sure if this is what you are looking for, but you can achieve this using the "Use hillshade effect" option in the layer properties of your floating point raster: Here is a snapshot of the layer alone: And another with imagery underneath


4

You're after elevation coloured, shaded relief? You could start by looking here: http://underdark.wordpress.com/2012/01/19/a-guide-to-beautiful-reliefs-in-qgis/ It's simple to use but doesn't offer much in the way of fine control. The results won't look too much like Imhof I'm afraid :( Hint: If your DEM is lat/lon then transform it to a projected CRS ...


4

I suppose that it is the result of r.shaded.relief. Have you set the correct resolution of your region of work (resolution of the SRTM layer, Res: 59.74514451 here) ? Resolution of the SRTM layer: Resolution of the region: Elevation; r.shaded.relief without grainy surface with the correct resolution


4

As you've probably found, removing clouds from Landsat imagery is not a trivial problem. There is a decent amount of scholarly research about methods for implementing masking and correction for clouds and their shadows. So due to the complexity of this issue, you probably won't find any one size fits all solutions that work perfectly out of the box. That ...


4

@Gerardo's answer is only correct at the equator. The gdaldem doc notes those scale values are for "LatLong projections near the equator" To calculate the scale or Z factor (inverse of scale) at other latitudes for a dem with vertical units in metres, you can use the following equations: s=111320*cos(latitude*pi/180) z=1/(111320*cos(latitude*pi/180)) ...


4

hillshade is based on the angle between the normal to the slope face and the sun rays. This angle is in a 3D space, so different combination of slope and aspect give the same value (like a cone with the sun ray for axis). In winter and in summer, both the sun elevation and the sun azimuth can be different at the same hour of the day. So you can have ...


3

Why not use the SRTM dataset to find out where you actually have the shadows? In the case you are referring to you might find that shadows are cast by clouds or other interference giving you a wrong (biased) basis for shadows in your landsat imagery. Find the potential shadow areas by using SRTM and make a hillshade raster. Make sure the sun angle and time ...


3

Combined pan-sharpening, contrast stretching, and gamma stretching functions If you have access to ArcGIS (and the Spatial Analyst Extension) you can use the technique described in this blog to "blend" DEM (or imagery) with shaded relief. The main disadvantage of this solution is that it is static; you need to produce an RGB raster from your DEM so if you ...


3

I don't really use QGIS very often so I don't know how it would be done there, but in Whitebox GAT, you would simply create a custom palette using the Palette Manager (Tools menu) to then display your hillshade image with: The palette above simply blends RGB(0, 50, 100) to RGB(255, 240, 170), although any desired custom palette is possible. Here is an ...


3

When working with DEMs in lat long coordinates with their units in decimal degrees and the vertical units in meters you have to set the "scale (ratio of vertical units to horizontal units) to 111120. In http://www.gdal.org/gdaldem.html they even suggests that this setting for DEMs with lantlon coordinates and vertical units in feet, the scale must be set ...


3

If you have an RGB map, you can use the pansharpening option in the symbology (RGB composite) of your RGB, selecting the Hillshade instead of a panchromatic image.


3

I would discourage you from perusing the course that you are on. In most cases there is some degree of useful reflectance information in every pixel. Before applying a dubious technique that just excludes what is perceived as shadow, you could first attempt to correct for the effect. I have had consistent success with the Minnaert correction in very steep ...



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