User Guide: Rivers edit

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This article describes river editing in Wikimapia Beta. River editing in Wikimapia Classic is no longer available. Wikimapia officially uses the term River to cover all other watercourse designations such as "canals", "streams" etc.

Rivers is a linear tool wherein you can mark waterways such as rivers, canals, streams etc. The marking of rivers is done by adding points and segments. Segments form the main "body" or "line" of the linear tool, while points link segments to each other. Points also enable segments to be laid in different directions. This method of marking is also used for the other linear features available in Wikimapia, such as Road, Railroad and Ferry.

The marking of rivers requires patience and meticulous attention to detail because of their complexity. Rivers can be as wide as lakes, while others can be as narrow as streams. Moreover, they can have straight courses or they can have tight "meandering" (curves) channels. Another characteristic of rivers is that they can form junctures (confluences) with other watercourses or split into smaller rivers (tributaries).

To address some of these factors, the River tool has an additional special feature that adds width to its segments. This feature is called riversides, and outlines the width of a river's channel (the distance between opposing "riversides") by adding a framework to segments. In essence, riversides are polygons for the river tool. When the riverside feature is activated, two smaller points, called "riverside handles", appear either side of an attached point at both ends of a segment. Just as opposing points are linked by segments; opposing riverside handles are linked with riversides. The riverside handles are flexible and can be manipulated to give two-dimensional shapes (or riversides) to segments.

When a river with riversides is saved, the Wikimapia map is updated to show the river with a fully rendered form, as opposed to a conventional thin blue line. In "Satellite" view the river is depicted with as a transparent blue channel. In "Map" view the river is defined with a solid blue channel.

Example

The image to the left shows the components of a riverside:
A. Segment.
B. Points. Located at either end of a segment.
C. Riverside handles. A pair, flanking one point and linked to an opposite pair. The lines joined with the riverside handles give river segments editable shapes.

A typical segment will consist of one line and two points. A riverside segment comprises of five lines and six points. Just as two standard segments share a point, a riverside segment will share a point and its pair of riverside handles.

On the right, the same river (viewed in "Map" view) is shown as saved with riversides activated.

Riverside components - A Segment B Segment points C Riverside handles

See paragraph above.

River with riverside in "Map" view

How to mark a river

Fig.1

1. Select the river tool by navigating to the menu bar at the top of your screen and then choosing "Edit map".
2. Click on "River" at the bottom of the menu (See Fig. 1). You shall then enter the edit mode.
3. To add a river, you will need to fix an initial point by clicking on the image of the river. Then select →
4. When you move the cursor, a segment will automatically extend from it. To set the segment, you will need to place another point along the river.
Repeat the process of adding points and laying segments along the centre line of the river, taking care to follow the contour of the river accurately and adding sufficient points to maintain a smooth line.
Hint add more points for meanders (bends in a river), and fewer points for straighter stretches.
If fewer points are used for meanders, the bend of the segment line will be more jagged. Remember: more points equals a flexible, meandering river.
5. Click "Save" at the bottom of the screen when you have finished.
Note: there will be a limit on how many points and segments you can add in one session.

Marking from an existing river

Fig. 2

To mark confluences, you may create a new tributary by clicking on an existing point and then selecting "Start new." (See Fig. 2) You may also add a new point in an existing segment, by clicking it and selecting "Insert point" from the menu.

Some hints

Select the highest zoom level available (z=19 or above) for the river you are editing.

If part of the river imagery is obscured by clouds or haze, it would be better to not mark that portion with the tool. However, if you have access to an alternative source that shows the complete watercourse, you may continue to mark it. When the imagery is eventually updated, the edited river should be fairly accurate; if not, it can always be tidied up afterwards

To ensure the river is marked as accurate as possible, the dots and segments should always be placed in the centre line of a river. This will also make certain that riverside segments will always be aligned correctly over the river image when they are included.

For rivers with islands, if both sides of the island provide sufficient space, then create smooth lines for both sides. If one side is definitely wider than another use your best judgment whether or not to create two lines.

For wide rivers with rapids, I tend to follow the 'racing' line, as long as the line entering and exiting curves or rapids is smooth.

It is crucial you use extra points to trace a river accurately, especially its curves, so that the final rendering is smooth and precise in appearance.