Support
How to define the islands of a plot for the GML?
Summary
When a cadastral plot has an island (an interior hole, for example a portion with a different use from the rest), that interior portion must be defined as a plot in its own right before creating the outer plot and exporting the GML. If this is not done, the GML does not recognise the island, validation reports come back negative, the Cadastre may report that the plot overlaps another one, or the area of the outer plot is calculated with the full cadastral figure without deducting the interior portion. This article explains the procedure with Plots > Define Islands and what to do when the island must also appear as an independent plot with its own area.
Applies to
MDT, MDT 25 and MDT 26 (current version). The documented cases expressly mention MDT and MDT 25; the remaining enquiries do not indicate a version.
Plots functions and GML export for the Cadastre.
Symptoms
When importing or validating a GML of plots with islands, the program does not recognise the islands and the validation reports come back negative.
When importing the GML into the Cadastre, a warning appears stating that the plot overlaps another one.
When the plots are generated, the outer plot takes the total cadastral area instead of deducting the interior portion (the island).
After defining the island and generating the GML, importing it into the CAD shows the plot with the net area, but the island is also required to appear as an independent plot with its own area.
Cause
The island (interior portion) had not been generated, defined or included as an independent plot before the outer plot was created or the GML was exported. In one case, the GML sent contained two adjoining plots and an island, but the plot filling that island had not been defined.
A single plot object cannot behave as an island and as an independent plot at the same time in the same drawing.
Solution
Case: defining the island so that the outer plot deducts its area
Run Plots > Define Islands and select the interior portion (the island).
Then create the outer plot. You will see that it already deducts the island from its area.
When you edit the outer plot, you will find that the area is already shown with the interior island deducted (actual area).
Make sure no hole is left without an associated plot: the plot filling the island must be defined before exporting.
Case: exporting the GML with the islands included
When exporting to GML, generate a separate GML file for each plot with its island (for example, one GML per selected plot).
Each GML will include the corresponding island and will reflect the actual area, that is, with the interior plot deducted.
Validate the GML in the Cadastre afterwards. If any error or warning appears, make a note of it to pass on to technical support.
Case: having the outer plot and the island appear as independent plots
If you need both the outer plot and the interior island to appear as independent plots, each with its own area (instead of one automatically deducting the other), bear in mind that the same plot cannot behave as an island and as a plot at the same time. The simplest approach is to work with two separate drawings:
One drawing with the plots together with their affected islands (net area, with the island deducted).
Another drawing with all the plots without islands (each one with its own independent area).
Generate the GML file from one drawing or the other, according to what you need in each case.
If the problem persists
If an error or warning still appears after validating the GML in the Cadastre, tell APLITOP technical support the exact message shown.
So that support can review how the plots and islands are laid out, attach the GML file when opening the enquiry: without it there is no way to check how the plots have been defined.
Category: Cadastre and GML · Level: Intermediate