I've followed every step by step to create slope map from DEM. I've set the projection to UTM 49S (my study site). But it always end up only two classes. 0 and 0-89.99999. I've tried many times. I don't know what's wrong. Have you ever been encountered this kind of failure? How to solve it?
zoolra Yes, this is definitely a projection issue. Make sure that you specify that your horizontal units are in METERS and your vertical units are in ... probably METERS also or whatever your DEM is in.
Hi mate, I've just been attempting to complete the slope and I'm encountering the same problem. I can't seem to find out how to change the units of horizontal and vertical could you give me some guidance for that?
Attn @namelessnitchy I do. It know what you mean - a straight distance would not be a slope. It has to be percentage or degrees or distance x divided by z
I could really use some help if anyone could offer any. I am trying to create a Least Cost Path model but using Tobler's Hiking function. However, for Tobler's function to work, I need negative slope values. Just creating a slope as normal gives all values as positive, because directionality is not specific. In other words, without the GIS knowing which direction we are facing, it cannot know what the true rise is when crossing a cell. When facing east, for example, the cell would have a positive slope. But the same cell should have a negative slope when facing west. Thus, to use Tobler's function, I need to be able to know the accurate true slope of each cell along the path, in the direction that the path is going. I know I may not be explaining the problem the best, but any help will be greatly appreciated.
Thank you!! I hace a question, is it possible to smooth the slope result? Im using a DEM but to a very specific area, and i would like to improve the resolution
Hi, I have a question about a slope map. I have now created a slope map from a digital elevation model. I was wandering if it possible to select an area with a certain slope, and then creat a new layer from the selected feature. So that my layer, for example, only covers the area with a slope steeper than 20 deg.
Yes… The way to do it would be to create a slope raster… And then use raster calculator to determine the slopes above a certain degree or percent… These would give you the slopes with the desired slow. If you want to convert back to vector you can.
HELLO! I have a tif DEM with different resolution in X and Y : cell size x =0.000222222222222222 cell size y=0.000111111111111111 with col=4501 and row =9001. The resulting slope map ,that I have, is a tif with : cell size x =0.000222222222222222 cell size y =0.000222222222222222 and col=4501 and row =4500 I don't understand why the slope matrix doesn't have the same dimensions as the input matrix .
Or else you are bumping up against resolution issues. With these cell sizes... I highly recommend changing the projection to UTM or something so your cell sizes will not be in decimal degree or whatever you have here, but in meters or centimeters.
@@Our__Earth Ok, thanks for the help, I will write geonet.esri.com. The problem exists even if I change the projection to UTM . It is possible that the slope-algorithm likes rectangular pixels better and therefore performs an initial sampling. In the meantime, I have used gdal to solve this problem. I noticed, the two slope maps (in arcpy and gdal) have similar mean , std-dev, etc...
+Felipe Salomón López Rodríguez There is some good information here: desktop.arcgis.com/en/arcmap/10.3/manage-data/subtypes/an-overview-of-subtypes.htm Sorry - just saw your note.
Hi, I hope you can help me. I am trying to Display the slope in percent rise, but if I run the tool set on percent it just gives the exact same answers or values as degrees. What am I doing wrong?
@@Our__Earth I have seen that, yes. I can't find my mistake... I follow your video exactly, except with percent rise, but the maximum "value" at the colour scheme under the contents pane is 90, so I think it is still in degrees
Ah! I understand .. .see this article from a few days ago - I hope it is helpful - support.esri.com/technical-article/000007693 Exporting raster values to a table. If not try posing your question on geonet.esri.com
Hello sir, I did a slope on a tin because my teatcher wanted the data to be in vectors but I do not know how to read the values because when I create the classes in simbology they come from 1 to 9.
Miguel - I am not sure about the procedures with making a slope map with correct symbology from a TIN - you probably should be using the TIN Slope tool - desktop.arcgis.com/en/arcmap/10.3/tools/3d-analyst-toolbox/tin-slope.htm
Felipe - I have created subtypes before and have set the ranges. Are you looking in ArcGIS Desktop help? If that is not helpful, then you might post a note to geonet.esri.com or to a regional GIS listserv in your area.
I´m trying to create my slope map from DEM in Arcgis but the results is so strange, please I need help, I dont know where I did wrong but I follow all the step. Can you help me?
+Albertina Give Are you sure you are using the correct units - meters or feet - some DEMs are in different vertical and horizontal units - some are feet, some are meters, some are decimeters... also - percent grade or rise/run - that is usually the problem.
+Albertina Give In your ArcMap session look at the metadata for those layers - especially in the map projection and coordinate system - it should give you the horizontal and vertical units that your data is in. I am fairly certain that this is where the problem is. If not you might pose this inquiry to the geonet.esri.com forum.
D - you can go to NebraskaMap - or if outside Nebraska - USGS National Map . GOV for the DEMs. You could do the same thing with Lidar as an image or grid.
Admasu - very sorry to hear this.... in this case I obtained the data from the Nebraska GIS portal. The complete lesson is on spatialreserves.wordpress.com and is the "siting a fire tower in the Loess Hills" lesson.
