A self-contained unit landscape is a portion of the territory where physical barriers limit and frame the view of the observer. The observer feels he is in a territorial compartment visually differentiated.
I think I worked with similar issues in order to frame ancient historical territories. Roman sources define territoria as the space where physical barriers limit and frame the view of the observer, so maybe you can implement the same solution. It is not a viewshed problem but a hydrological microbasin one, at least in my case study. You can read my proposal to solve this matter in page 287-292 of my PhD dissertation (https://cadic-conicet.academia.edu/JoanNegre/PhD-Thesis).
I hope this will help.
I agree with Diana Patricia. You can treat the areas as specific units and based on your interest and treat them as single units. However, you can check from ESRI- you will get more technical support.
Hey! I didnt understand well... Do you want to define homogeneous landscape units in a 2D map (e.g. landscape classification)? Or are you talking about 3D analysis of scenery? Could you be more specific? Sounds interesting...
If I understood correctly, I think you should start by defining some variables, meaning the characteristics that an observer uses to define or perceive the limits and thus creates in his view a unit landscape, such as biophysical particularities, vegetation cover type, geomorphology, patterns?, spatial distibution of elements. If you define variables and then try to give them weights, it would be like transforming qualitative information into quantitative; I suppose this is the main concept from which you would start constructing your way, your methodology..as for the methods, I think that a thorough literature search would do. My answer is just intuitive, at a first glance. I hope I understood well your question and I hope it helps. Sincerely, when I read you question, it just crossed my mind why not integrating those variables even with a DEM, more specifically calculating the field-of-view from a DEM and then intersecting, combining that data with your variables weights...Good work!
I think your looking for a method to define landscape units. The problem is interesting in that the cultural landscape can become the unit of action planning and territorial management. I think you should use 3D GIS analysis, integrating the highest number of spatial variables. The topic seems very interesting
Yours is a typical "viewshed analysis" problem. I find the two tools available for visibility analysis in ArcGIS, Viewshed and Observer Points, very practical (and many other GIS softwares should have good enough functions) but I would advise you to take a couple of a priori decisions: it is critical to have a good understanding of the tool's options (Point data, OFFSETA, OFFSETB, VERT1, VERT2, AZIMUTH1, AZIMUTH2) and to make good use of them, and also do choose an appropriate representation of the landscape's surface, meaning that you should not use a topographic model of the study region, but instead you should use a surface model (topography+vegetation+buildings) such as high resolution radar products (e.g. TanDEM-X - http://www.dlr.de/hr/en/desktopdefault.aspx/tabid-2317/3669_read-5488/). The downside of this choice is that those are usually (well) paid products. A second best approach to surface models is to use free remote sensing products such as SRTM or ASTER and to 'add the volumes' corresponding to built structures and dense vegetation patches. Hope this information helps and good luck!
Regarding my question, “How can I calculate with GIS landscape units that are spatially self-contained?” , I would like to do some clarifications.
I'm not trying to define landscape units. I'm trying to define self-contained spaces or compartments inside which we can identify different landscape units (although this depends on the scale at which we are working). What I'm trying to do is to model the territory in different compartments, visually independents. If you allow me the metaphor, I try to define "the different rooms of the territory".
This is not to define landscape units or calculate the viewshed from a point or road but cartographically delineate areas where observers feel within them.
I have defined these compartments manually supporting me in ArcScene and fieldwork. But I would like to model these visual compartments automatically using GIS.
Emilio, I think you can solve your question dealing with hydrological tools in order to create small watersheds or drainage basins. These microbasins act as territorial compartments, visually independents.
I think Joan Negre's answer is helpful but what about background slopes that, although outside the drainage basin, are visible from inside the basin? I mean, there's a foreground (and those areas should be inside the drainage basin) but there's also a visible background (and if you need to consider these visible areas outside the drainage basin, the hydrology tools are not enough.
Maybe if you start by the drainage basins and them locate a grid of observer points inside, in order to estimate its viewshed, you will get closer to what you need.
Nevertheless, I still think its important to use a surface model rather than a relief model.
Hope this helped, good luck!
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