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Hi Dan! Thank you very much for your reply. I intend to use DEM 1x1 m, which is derived from Lidar data. To calculate the slope of a road segment, should I use "Add Surface Information Tool" or any other script, maybe in Python? Thank you very much! Klemen
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02042020
11:41 PM

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Hello, My name is Klemen. I work a lot with road networks in 3D GIS. I would like to calculate an accurate slope for road network lines. I use the tool "Add Surface Information" (ArcGIS for Desktop). As a result, in the areas of steeper slope, the slope value of road segment differs so much from the slope of underlying raster. There is an example in the attached figure. We can see an area of 9 cells. The size of one cell is 5 x 5 meters. Red numbers represent the values of elevations (in meters) for each cell. Blue numbers represent the values of slope for each cell (in degrees). The green line is one road segment. It's length in 2D GIS is only 9,189 meters. The green segment crosses four cells. After using the tool "Add Surface Information", the result for 3D length is 10,99 meters and for average slope is 65,61 degrees. How can the value of average slope of road segment differ so much from the slope of raster cells (blue valus)?? I'm thinking that the solution of my problem could be the use of code in following support: How To: Calculate the instantaneous slope of a linear feature across a surface . I would like to use that code in ArcPy, but my colleagues told me, that the existing code is not written in ArcPy (my personal knowledge of Python is not good). Do you know this code in Python (ArcPy)? I would really like to try it. Thank you very much! Klemen
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02042020
12:44 AM

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4

584

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Dear Sirs, My name is Klemen. I work a lot with road networks in 3D GIS. I would like to calculate an accurate slope for road network lines. I use the tool "Add Surface Information" (ArcGIS for Desktop). As a result, in the areas of steeper slope, the slope value of road segment differs so much from the slope of underlying raster. There is an example in the attached figure. We can see an area of 9 cells. The size of one cell is 5 x 5 meters. Red numbers represent the values of elevations (in meters) for each cell. Blue numbers represent the values of slope for each cell (in degrees). The green line is one road segment. It's length in 2D GIS is only 9,189 meters. The green segment crosses four cells. After using the tool "Add Surface Information", the result for 3D length is 10,99 meters and for average slope is 65,61 degrees. How can the value of average slope of road segment differ so much from the slope of raster cells (blue valus)?? I'm thinking that the solution of my problem could be the use of code in following support: How To: Calculate the instantaneous slope of a linear feature across a surface . I would like to use that code in ArcPy, but my colleagues told me, that the existing code is not written in ArcPy (my personal knowledge of Python is not good). Do you know this code in Python (ArcPy)? I would really like to try it. Thank you very much! Klemen
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02032020
03:24 AM

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Hi Nobbir Ahmed! The geographic extent is the whole city of Vienna (capitol city of Austria). Here are two links to both shapefiles: public transport lines and public transport stations. Thank you very much!
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05302019
05:02 AM

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Hello and thank you very much for your answer! I enclose a screenshot. I've tried different projected coordinate systems, but the answer is always the same. And the dropdown list for Geographic Transformation never appears. If I type certain geographic transformation, the answer is "invalid geographic transformation". I work with ArcMap. Would it be better to use ArcGIS Pro?
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05292019
02:29 AM

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Thank you very much for your answer! And I apologize for my late answer. You are right. My transformation from WGS 84 to Clarke 1866 was not correct. But here I have another problem. I can not perform transformation from WGS 84 to any other coordinate system (I must do the transformation because WGS 84 is not appropriate for network analysis). Certainly, I use tool Project. After I define a Geographic Transformation, I get the information: invalid geographic transformation? Could be something wrong with my original layers in WGS 84? But they are official from Austrian government.
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05282019
04:34 AM

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Hi, I have a problem that I can not solve. I have pretty much experience with ArcGIS, especially with transportation analysis. I have one layer of multimodal stops, where is possible to change transportation mode, i.e. between bus and metro. In network dataset such stops represent connection points between bus and metro. Therefore such stops must be assigned to both connectivity groups  bus and metro. One important condition is that these points must be located exactly on the line of transportation network. I tried to do it by geoprocessing tool Snap. It looked good, but when I zoomed in, I found out that the points do not lie exactly on the line. I tried many other tricks, but no success. Then I used tool Locate Features Along Route. The result was a table, which I used to perform a Display Route Events. The result was a point layer Route Events. Only in this layer all points (multimodal stops) were located exactly on the transport lines, even when I zoomed in to maximum. But..... I can not use the pointlayer Point Events as an input layer for network dataset. I must change it to shapefile or feature class. But then  points move a little bit away from transport lines. I am in a kind of trap and I can not go on with my work. Thank you very much for your help! Klemen
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