Digitising A New Polyline

(This option is not available on the Freeware version)

This option is used to add new vectors (polylines) to the vector drawing, by clicking the vertex positions with the mouse - a process called digitizing.

Enter the digitising mode by clicking the Digitise New Polyline toolbar button (or the Vector->Digitise->Digitise A Polyline menu option).
The cursor will change to a Digitising cursor crosshair to indicate that the digitising mode is in effect.

First click the mouse at the start point for the line. After you click the first point WinTopo Pro will show a thin black line stretching from that point to the cursor crosshair. This line stretches as you move the cursor. The line shows where the vector will be placed when you next click the mouse. The method of stretching lines to the cursor position is termed rubber banding because it is like streching a rubber band. It is very useful for accurately positioning your vector before clicking it onto the drawing.

After you click the second point the rubber banding will be shown from that point, ready for the third point, and so on. You can keep clicking points to make up a polyline. The idea is to draw out the desired features from the raster image, which is displayed under the vector drawing.

To finish the polyline and start another one, you can click the right mouse button. This will stop rubber banding from the last point, and allow you to click the first point of the next polyline. Alternatively, you can press the Esc key, or click the Digitise New Polyline toolbar button again.

Snap Modes

You will notice a small square within the crosshair Digitising cursor cursor. We call this the target square, because it shows the actually location that will be selected by the next mouse click. When no snap mode is being used the target square will sit at the centre of the crosshair, but when a snap mode is in effect the target square will jump to the appropriate feature for the particular snap mode. Snap modes are very useful for accurately placing the vector end points. See Snap modes for more information.

Colour

The default colour for the new polylines is Black, but you can choose any colour by clicking the Digitising Colour Picker toolbar button. This makes the cursor change to a until you click on a pixel within the image. The colour of the selected pixel is used.

You can also select the digitising colour from the Digitising Options window.

Undo

If you make a mistake, or want to redo a point, then you can click the Undo button undo toolbar button. The last digitising operation will be undone.


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