topic Re: Viewshed Analysis and Statistics in ArcGIS Spatial Analyst Questions

Viewshed Analysis and Statistics

RobertoFilloramo — Mon, 12 Nov 2018 15:43:03 GMT

Hi,

I am working with ArcGIS 10.1, I determined the viewshed and the fuzzy viewshed for 10 points placed along a river, my willing is to create a statistics (table or graph), using the results, in which it is possibile to see the percentage of overlapping between the visible area (according each point) and the percentage of visibility for each point according the landscape in all cardinal points. Is it possible? Any suggestions?

Thank you

Re: Viewshed Analysis and Statistics

DanPatterson_Retired — Mon, 12 Nov 2018 17:38:22 GMT

overlaps can be determined using Combine amongst other approaches,

Percentages require a number relative to a total.

So everything can be derived if you can provide the inputs. A screen grab of where things might be causing you problems might help

Re: Viewshed Analysis and Statistics

RobertoFilloramo — Tue, 13 Nov 2018 10:43:45 GMT

Thank you Dan for replying me... So, I worked around with the Combine tool, to be honest it is not very clear to me (also from the Esri's Help about it). Attached you will find the result, I used the tool for the fuzzy viewshed applied to the green point (triangles). If the table should show the overlapping area, I believe that the result is wrong.

Concerning the percentage, I agree with you on the "number relative to a total" yet the viewshed and fuzzy viewshed are 0 and 1 or on the scale from 0 to 1 (as in the figure below).

Re: Viewshed Analysis and Statistics

DanPatterson_Retired — Tue, 13 Nov 2018 12:04:12 GMT

arcmap 10.1 ...

So I suspect that Viewshed 2 isn't available

How Viewshed 2 works—Help | ArcGIS Desktop

You appear to have limited the viewshed parameters in your analysis (limited horizontal distance?) So it is hard to tell what information you provided for your observer points and the viewshed itself).

You have an area with apparently overlaying viewsheds, but you didn't provide any information on what you used in the combine analysis

Using Viewshed and Observer Points for visibility analysis—Help | ArcGIS Desktop

I suspect combine can be omitted if this is the type of analysis you are trying to do (from viewshed 2 help)

Re: Viewshed Analysis and Statistics

RobertoFilloramo — Tue, 13 Nov 2018 14:31:28 GMT

Sorry I forgot to write before... the parameters are OFFSETA 1,65; OFFSETB 1,65; RADIUS2 15km.

Anyway, in arcmap 10.1 there is just the viewshed tool (not viewshed 2).

Therefore, I applied the combine tool to the viewshed results, since I used a tool planned for acquired the fuzzy viewshed I thought that perhaps my parameters were considered more in the viewshed result then in the fuzzy one. I presume that it works, as in the viewshed 2 sample that you posted.