Manifold GIS; Building and Editing Tools
We will dedicate this post to see the tools to build and edit data with Manifold, in this field GIS solutions are very weak, while limiting the "infinitesimal" precision of CAD tools since when stored in a database it requires that limit your "precision" to a number of decimal places. It is clear that for practical purposes two tenths are enough ... and in some cases three.
But you would expect from a tool that has the minimum solutions to create and modify geometries. Let's see what it has:
1. Creation Tools
These are automatically activated when selecting a component, and are as follows:
It is based on creation of three types of objects: areas (polygon), lines and points; with the variant with respect to ESRI that a component can carry different type of objects in each one there Feature class It can only be of one type of these three objects.
Then there are variants of creation that go in this order:
- Insert area (based on points), equivalent to boundary of AutocAD or Microstation shape
- Insert freeform
- Insert free line
- Insert line (based on points)
- Insert non-grouped lines, equivalent to AutoCAD line and Microstation smartline without the option to group
- Insert points
- Insert box
- Insert frame based on a center
- Insert circle
- Insert circle based on center
- Insert ellipse
- Insert ellipse based on a center
- Insert circle based on data (center, radius). The latter is very practical in GIS because it is used a lot for the measurement from a vertex or triangulation ... although it falls short because there is no intersection alternative in the snaps.
In addition to this is the input panel by means of the keyboard that I showed in the previous post which is activated with the "insert" button on the keyboard.
2. Snap tools.
These are almost enough, and among the best they have is the option to choose several at the same time ... aspect that is limited in Microstation. To activate or deactivate the tentative (snap) button "space bar"of the keyboard.
- Snap to lattice (latitudes and longitudes), if the lattice is activated, allows to capture as a tentative point the intersections of a mesh.
- Snap to grid (xy coordinates), similar to the previous one.
- Snap to polygons
- Snap lines
- Snap to points
- Snap to objects, this is equivalent to the "nearest" of AutoCAD, in which any point is captured on the edge of a polygon or line.
- Snap to the selection, this is one of the best commands, because it allows to snap only on the selected objects, allowing combinations of the previous ones.
Obviously, the "intersection", "midpoint" and "centerpoint" alternatives are not very necessary, tangents do not seem to be so necessary in GIS, nor "quadrant"
3. The editing tools
- Add vertex
- Add vertex on the line
- Delete vertex
- Remove vertex and do not join ends
- Cut section
- Delete section
- Cutting off
- Segment objects
It takes many tools, such as precision moving, parallel (offset) ...
4. Topological control
This is a tool of the that I talked about before, which allows objects to associate neighborhood criteria; such that when modifying a boundary the neighbors are accommodated to that modification.
This was one of the major limitations of earlier versions of ArcView 3x; ArcGIS 9x already integrates this although it seems to me that only if the Feature class is within a Geodatabase, as well as Bentley Map and Bentley Cadastre.
There is also a solution called "topology factory" that allows to do very extensive topological cleaning, between excess lines, overlapping objects, loose geometries and the option to solve them manually or automatically. is in "drawing / topolgy factory"
In conclusion, as long as Manifold does not add a couple of additional tools, it will be preferable to do the editing with a CAD tool, and bring to the GIS only the shape or points to build there. In this, the choice of GvSIG in trying to imitate the most important tools of construction of AutoCAD instead of assuming that they occupy the users.
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