AfricaEvents29November2008 - Revision history

Wiki-Brendonwp: /* First we show you */

2008-12-01T09:07:57Z

First we show you

2008-12-01T09:05:47Z

What have I learned?

2008-12-01T09:01:34Z

Now You Try!

2008-12-01T08:56:10Z

What have I learned?

2008-12-01T08:53:24Z

What have I learnt?

2008-12-01T08:52:46Z

What have I learnt?

2008-12-01T08:51:18Z

Now You Try!

2008-12-01T08:44:07Z

First we show you

2008-12-01T08:36:13Z

Editing Vector Data

2008-12-01T08:29:15Z

What have I learned?

@@ Line 644: / Line 644: @@
 === First we show you ===
 * Select the rivers layer in the Legend panel on the left.
-* Click on the blue Pencil icon on the leftmost toolbar on the bottom row or <menu option>.
+* Click on the blue Pencil icon (Toggle Editing) on the leftmost toolbar on the bottom row or <menu option>.
 * Now click on the <edit vertices> icon. Notice how the river lines have suddenly sprouted small circles wherever the line changes direction.  These are the vertices - if you have used a drawing program before you might have seen something like this.
 * Drag the vertices of the rivers to align with the provincial boundary.
@@ Line 650: / Line 650: @@
 * Click on the add vertices icon.  Now click on the river wherever more vertices are needed.
 * When you have enough vertices go back to "Edit Vertices" and move them where they need to be.
-* Now save you changes using <>.
+* Now save your changes using by clicking on "Toggle Editing" and selecting "Save" on the dialog box.
 === Now You Try! ===

@@ Line 658: / Line 658: @@
 === What have I learned? ===
-You have now learned how to edit vector data in QGIS using the Add Vertices and Move Vertices functions.
+You have now learned how to edit vector data in QGIS using the edit toolbar.  Editing data may not be as immediately rewarding as setting up a map onscreen or for printing, but it is important to be able to do this to get rid of errors that will spoil all the effort put into drawing up an impressive map!
 [[Category:Africa]]

@@ Line 653: / Line 653: @@
 === Now You Try! ===
-Go to Gauteng and bring up the JPEG map sheets behind the roads.  Have a look at the roads and notice where the vectors are not aligned with the base map.  Use the edit features to correct the roads vectors.
+Go to Gauteng and bring up the JPEG map sheets behind the roads.  Have a look at the roads and notice where the vectors are not aligned with the base map.  Use the skills you have used to correct the roads vectors.  Try other tools like Split Features, Move Features and other to see what they do.
 Then look at the rivers and provincial boundaries again.  See if you can find another place where the two are not aligned.  Experiment with the Snapping Options under Project Properties.  Use the Measure Length tool to decide on reasonable initial tolerance values.

@@ Line 658: / Line 658: @@
 === What have I learned? ===
+You have now learned how to edit vector data in QGIS using the Add Vertices and Move Vertices functions.
 [[Category:Africa]]

@@ Line 247: / Line 247: @@
 Notice how you can zoom right in to vector data, and a point remains a point and a line remains a line.  When you zoom in to the satellite image it rapidly appears "blocky" compared to the 50 000 map sheets. Zoom in enough and even the map sheet raster blocks can be seen.  This is a basic difference between vector and raster data.
-=== What have I learnt? ===
+=== What have I learned? ===
 You have learnt to set scale-dependent rendering so that data sets are displayed at appropriate scales, how to add raster data and set raster display options.

@@ Line 634: / Line 634: @@
 QGIS calculates the effect of the projection before displaying the data and doesn't make any changes, so you can try anything you like!
-=== What have I learnt? ===
+=== What have I learned? ===
 You have learnt how to set an on-the-fly projection for display in QGIS, and how to use EPSG codes to rapidly find a specific projection. Remember, if you are trying to develop a map for use in the field you will need to use a projection specific to South Africa.

← Older revision		Revision as of 08:51, 1 December 2008
Line 653:		Line 653:

	=== Now You Try! ===		=== Now You Try! ===
		+	Go to Gauteng and bring up the JPEG map sheets behind the roads. Have a look at the roads and notice where the vectors are not aligned with the base map. Use the edit features to correct the roads vectors.
		+
		+	Then look at the rivers and provincial boundaries again. See if you can find another place where the two are not aligned. Experiment with the Snapping Options under Project Properties. Use the Measure Length tool to decide on reasonable initial tolerance values.

	=== What have I learned? ===		=== What have I learned? ===

← Older revision		Revision as of 08:44, 1 December 2008
Line 643:		Line 643:

	=== First we show you ===		=== First we show you ===
		+	* Select the rivers layer in the Legend panel on the left.
		+	* Click on the blue Pencil icon on the leftmost toolbar on the bottom row or <menu option>.
		+	* Now click on the <edit vertices> icon. Notice how the river lines have suddenly sprouted small circles wherever the line changes direction. These are the vertices - if you have used a drawing program before you might have seen something like this.
		+	* Drag the vertices of the rivers to align with the provincial boundary.
		+	Notice that we don't have enough vertices to do this exactly.
		+	* Click on the add vertices icon. Now click on the river wherever more vertices are needed.
		+	* When you have enough vertices go back to "Edit Vertices" and move them where they need to be.
		+	* Now save you changes using <>.

	=== Now You Try! ===		=== Now You Try! ===