Difference between revisions of "Migration of unstructured DTP maps"

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===Delete redundant objects===
===Delete redundant objects===
There are redundant objects in the immported map.
There are redundant objects in the immported map. So, for example, streets consist of two or more geometrically identical lines.

Revision as of 09:48, 18 October 2011

Open OCAD file

Open crete-emty.ocd file. The file is located in the training data in the following directory crete_ocad.

Set Map Scale

Set scale to 1:100 000 (Map -> Set Scale and Coordinate System).

-> OK

Definition of a Symbol Set

In the open OCAD file is already defined a symbol set. Exemplary in this document is the definition of the new point symbol Point of interest is described.

Open scanned legend as background map

Open the TIFF file legende_crete.tif from the directory crete_backgroundmaps as backgroundmap (Backgroundmap -> Open).

Create New Symbol

Symbol -> New

Choose Point Symbol from New Symbol dialog box:

-> OK

Enter symbol number and symbol description. Click the button Edit:

The symbol editor will show.

View -> Hide Show Entire Map and Show Map Grid

In the next step, the legend symbol must be placed into the origin of coordinates of the symbol editor (red arrow in fig):

Background Map -> Adjust (Shortcut F):

  1. Mouse click Point of Interest in background map.
  2. Mouse click origin of coordinates from drawing area.
  3. Execute move with enter key.
hint -Most of the fine-tuning is done in several adjust steps.
-For fine-tuning it is recommended that the coordinate grid map show grid is shown.

Select the geometry Area and the Color 0: Pikto Orange in symbol editor:

Then just draw the symbol with the straight line mode File:StraightLineMode.JPG from the drawing tool.

-> Close symbol editor

The dialog box Point Symbol is shown again.

-> Icon

Create an Icon:

-> OK

The dialog box Point Symbol is shown again.

-> OK

Remove background map (Backgroundmap -> Manage):

-> Remove and Close the dialog

OCAD learning videos:

video availableDifferent point symbols
video availableDifferent lines symbols
video availableDifferent area symbols
video availableDifferent text symbols

Import DTP map as PDF

Import PDF file ICV_crete_Mapsheet1_West_fhd.pdf from the directory crete_fh (File -> Import).

-> Open

The import side which should be imported must be specified, becauce it is multi-page PDF.

-> OK

View -> Show Entire Map show entire map

The import map is displayed. However the map is not georeferenced.

Open georeferenced Background Map

Open the georeferenced TIFF file kreta_osm_with_checkpoints.jpg from the directory crete_osm as background map (Backgroundmap -> Open).

Because it is a georeferenced background map, a dialog box appears with the question if the new shift (horizontally and vertically according to the Easting and Northing) shall be used as the card center.

-> Ok

View -> Show Entired Map show entire map

The Crete map the the georeferenced background map are shown. But the Crete map is still not correctly georeferenced.

The interactive georeferencing from the Crete map success in the next section.

Georeferenzing and Rubbersheeting

Change the View into Draft Mode (View -> Draft Mode).

In the toolbar, a bar appears with two controllers. With the upper controller (M=Map) can adjust the transparency of the map and with the lower controller (B=Background Map) can adjust the transparency of the background map.

Coarse adjustment using Affine transformation

In a first step, the imported map was fitted coarse with an affine transformation in the georeferenced background map (Map -> Transform -> Afine).

  1. Mouse click into the map.
  2. Mouse click on the appropriate point on the background map.
  3. Execute transformation with enter key.

hint At the affine transformtaion the maximum of 12 reference points can be defined, by repeating step 1 and 2 until the transformation is triggered by the enter button.

Fine adjustment with Rubbersheeting

In the secont step the map fitted as exactly as possible with rubbersheeting transformation on the georeferenced background map (Map -> Transform -> Rubbersheeting)

hint This function is only available on OCAD version 10.2.4 or newer.

OCAD learning videos:

video availableRubbersheeting Transformation

First the rubbersheeting perimeter must be determined (Define -> Draw rubbersheeting perimeter on map)

Parimeter is displayed as a blue frame in the drawing area:

When a parimeter is defined, rubbersheeting points can be added interactively or from loaded from a file.

Add rubbersheeting points interactive:

  1. Mouse click into the map.
  2. Mouse click on the appropriate point on the background map.

Rubbersheeting points are shown with a red and green crosshair and a blue connection line. In the transformation, the objects moved from the red to the green dot.

Depending on the needs the points can be deactivated, removed or saved. The deactivation is done by mouse click on the first column in the table. Unused points are shown gray in the drawing area.

Execute the transformation by clicking the Transform button.
If the result is satisfactory, the dialogue can be closed.
Otherwise there are the following possibilities:

  • Undo the transformation an optimize rubbersheeting points (add, deactivate, delete)
  • Use the result as a starting point for further transformation with new points.

Transform PDF image objects in OCAD objects

Automatic conversion

With the function Convert Imported Layers to Symbols (Map -> Convert Imported Layers to Symbols) icons can be automatically converted due to their affiliation with the appropriate symbol into OCAD objects with the appropriate symbol.

In the dialog box Convert Imported Layers to Symbols the translation table crete.crt from the crete_crt directory needs to be loaded.

-> Execute

Manuall conversion

In the automatic conversion wrong symbols assigned from objects lying on wrong layers. In the example below, the Greek name of the attraction Tilissos is falsely attributed to the layer with the black instead of red font.

Select object:

Select correct symbol from symbol box:

Click Change Symbol in stadard toolbar to assign the object to the right symbol

Transform area-point objects in OCAD point objects and delete redundant objects

In DTP programms point objects are often defined as an area object. Thus make a situation worse by the map tracking. Therefore, these objects should be converted into point objects. These have only coordinates and can be easily deleted or moved at a tracking.

In the automatic conversion these objects have been transformed as a workaround in area objects (for example 1601.1 chapel area). In the symbol set they are defined as single point and area symbols. First select all objects with the area symbol 1601.1 chapel area (Symbolbox -> symbol 1601.1 chapel area -> context menu -> Select Objects by Symbol).

Then the conversion occur in a point object(Map -> Convert Area or Line Objects to Point Objects), while the symbol 1601.1 chapel area have been selected.

-> Execute

hint In case of imported signatures, consisting of multiple surfaces, before the conversion the surplus areas have to be removed, so that the equivalent to only one object is created to the appropriate place.

This process is explained using the example of the windmill. The imported windmill signatures are part of five faces: one tower and four rotor blades:

Befor converting into a point object the four rotor blades of all windmills have to be selected and deleted

Select the symbol 1702.1 windmill area in sybmol box.
Choose the function Select Object by Property (Map -> Select Objects by Property).

Settings: Select: Object with a selected symbol Condition: Number of vertices = 4

-> Select and Close dialog box

The rotor blades of all windmills were selected.

Delete selected objects with Delete button.

The ramaining area objects can now be transformed into point objects as described in the first part of the chapter.

Delete redundant objects

There are redundant objects in the immported map. So, for example, streets consist of two or more geometrically identical lines.