[QGIS Commit] r9910 - docs/trunk/english_us/user_guide
svn_qgis at osgeo.org
svn_qgis at osgeo.org
Tue Dec 30 09:15:14 EST 2008
Author: timlinux
Date: 2008-12-30 09:15:13 -0500 (Tue, 30 Dec 2008)
New Revision: 9910
Modified:
docs/trunk/english_us/user_guide/working_with_vector.tex
Log:
Revised working with vector data chapter
Modified: docs/trunk/english_us/user_guide/working_with_vector.tex
===================================================================
--- docs/trunk/english_us/user_guide/working_with_vector.tex 2008-12-30 08:29:07 UTC (rev 9909)
+++ docs/trunk/english_us/user_guide/working_with_vector.tex 2008-12-30 14:15:13 UTC (rev 9910)
@@ -84,7 +84,7 @@
\begin{Tip}\caption{\textsc{Layer Colors}}
\qgistip{When you add a layer to the map, it is assigned a random color. When
-adding more than one layer at a time, different colors are assigned to each. }
+adding more than one layer at a time, different colors are assigned to each layer. }
\end{Tip}
Once loaded, you can zoom around the shapefile using the map navigation tools.
@@ -145,7 +145,7 @@
\label{label_postgis}
PostGIS layers are stored in a PostgreSQL database. The advantages of PostGIS
-are the spatial indexing, filtering and query capability. Using PostGIS,
+are the spatial indexing, filtering and query capabilities it provides. Using PostGIS,
vector functions such as select and identify work more accurately than with
OGR layers in QGIS.
@@ -186,7 +186,8 @@
\\
\hline Host \index{PostgreSQL!host}
& Name of the database host. This must be a resolvable host name the same as
-would be used to open a telnet connection or ping the host. \\
+would be used to open a telnet connection or ping the host. If the database is
+on the same computer as QGIS, simply enter 'localhost' here. \\
\hline Database \index{PostgreSQL!database} & Name of the database. \\
\hline Port \index{PostgreSQL!port}& Port number the PostgreSQL database
server listens on. The default port is 5432.\\
@@ -262,14 +263,14 @@
QGIS requires that PostgreSQL layers contain a column that can be
used as a unique key for the layer. For tables this usually means
-that the table needs a primary key, or have a column with a unique
+that the table needs a primary key, or a column with a unique
constraint on it. QGIS additionally requires that this column be of
type int4 (an integer of size 4 bytes). If a table lacks these items,
the oid column will be used instead. Performance will be improved if the
column is indexed (note that primary keys are automatically indexed in
PostgreSQL).
-If the PostgreSQL layer is a view the same requirements exist, but
+If the PostgreSQL layer is a view, the same requirements exists, but
views don't have primary keys or columns with unique constraints on
them. In this case QGIS will try to find a column in the view that is
derived from a table column that is suitable. If one cannot be found,
@@ -299,7 +300,7 @@
\begin{Tip}
\caption{\textsc{Exporting datasets from PostGIS}\index{PostGIS!Exporting}}
\qgistip{Like the import-tool \filename{shp2pgsql} there is also a tool to export
-PostGIS-datasets into shapefiles: \filename{pgsql2shp}. This is shipped within your
+PostGIS-datasets as shapefiles: \filename{pgsql2shp}. This is shipped within your
PostGIS distribution.}
\end{Tip}
@@ -351,7 +352,7 @@
ogrinfo --formats | grep -i post
\end{verbatim}
-If you like to use PostgreSQLs \filename{COPY}-command instead of the default
+If you like to use PostgreSQL's \filename{COPY}-command instead of the default
\filename{INSERT INTO} method you can export the following
environment-variable (at least available on \nix and \osx):
\begin{verbatim}
@@ -479,7 +480,7 @@
Within this dialog you can style your vector layer. Depending on the selected
rendering option you have the possibility to also classify your mapfeatures.
-At least the following styling options apply for nearly all renderes:
+At least the following styling options apply for nearly all renderers:
\begin{description}
\item[Outline style] - pen-style for your outline of your feature. you can
also set this to 'no pen'.
@@ -494,19 +495,25 @@
Once you have styled your layer you also could save your layer-style to a
separate file (with \filename{*.qml}-ending).
-Therefor use the button \button{Save Style \ldots}. No need to say that
+To do this, use the button \button{Save Style \ldots}. No need to say that
\button{Load Style \ldots} loads your saved layer-style-file.
+If you wish to always use a particular style whenever the layer is loaded,
+use the \button{Save As Default} button to make your style the default. Also,
+if you make changes to the style that you are not happy with, use the \button{Restore
+Default Styel} button to revert to your default style.
+
\minisec{Vector transparency} \label{sec:vect_transparency} \index{vector layers!transparency}
QGIS \CURRENT allows to set a transparency for every vector layer. This can be done with
-the slider \slider{Transparency}{0}{20mm} inside the tab \tab{symbology} (see fig. \ref{fig:vector_symbology}).
+the slider \slider{Transparency}{0}{20mm} inside the \tab{symbology} tab (see fig. \ref{fig:vector_symbology}).
This is very useful for overlaying several vector layers.
\subsubsection{Metadata Tab}
The \tab{Metadata} tab contains information about the layer, including specifics
about the type and location, number of features, feature type, and the editing
-capabilities. The \guiheading{Layer Spatial Reference System} section, providing projection information, and the \guiheading{Attribute field info} section,
+capabilities. The \guiheading{Layer Spatial Reference System} section, providing
+projection information, and the \guiheading{Attribute field info} section,
listing fields and their data types, are displayed
on this tab. This is a quick way to get information about the layer.
@@ -539,7 +546,7 @@
buttons to set the font and color. You can also change the angle and the
placement of the text-label.
-To change the position of the font relative to the feature:
+To change the position of the text relative to the feature:
\begin{enumerate}
\item Click on the \tab{Font} entry.
@@ -759,10 +766,10 @@
Within the \tab{Attributes} tab the attributes of the selected dataset can be
manipulated. The buttons \button{New Column} and \button{Delete Column} can be
used, when the dataset is in editing mode. At the moment only columns from
-PostGIS layers can be edited, because this feature was not supported by
-the OGR library so far.
+PostGIS layers can be edited, because this feature is not yet supported by
+the OGR library.
-The button \button{Toggle editing mode} toggles this mode.
+The \button{Toggle editing mode} button toggles this mode.
\minisec{edit widget}
@@ -773,16 +780,16 @@
widgets are:
\begin{itemize}
-\item line edit: a edit field which allows to enter simple text (or restrict to
+\item line edit: an edit field which allows to enter simple text (or restrict to
numbers for numeric attributes).
-\item unique value: a list of unique attribute values of all preexisting features
-is produced and presented in a combobox for selection.
+\item unique value: a list of unique attribute values of all pre-existing features
+is produced and presented in a combo box for selection.
\item unique value (editable): a combination of `line edit' and `unique value'.
-The edit field completed entered values to the unique value, but also allows
+The edit field completes entered values to the unique value, but also allows
to enter new values.
\item value map: a combobox to select from a set of values specified in the
-\texttt{value} column the \tab{Attributes} tab. The possible values a
-delimited by a semicolon (e.g. \verb|high;medium;low|). It's also possible
+\texttt{value} column the \tab{Attributes} tab. The possible values are
+delimited by a semicolon (e.g. \verb|high;medium;low|). It is also possible
to prepend a label to each value, which is delimited with an equal sign (e.g.
\verb|high=1;medium=2;low=3|). The label is shown in the combobox instead of
the value.
@@ -802,7 +809,7 @@
\subsection{Editing}\index{editing}
-QGIS supports basic capabilities for editing spatial data. Before reading any
+QGIS supports basic capabilities for editing vector geometries. Before reading any
further you should note that at this stage editing support is still preliminary.
Before performing any edits, always make a backup of the dataset you are about
to edit.
@@ -827,9 +834,11 @@
\item A general, project wide snapping tolerance can be defined choosing \mainmenuopt{Settings} -> \dropmenuopttwo{mActionOptions}{Options}
In the \tab{Digitizing} tab you can select between to vertex, to segment or to vertex and segment
as default snap mode. You can also define a default snapping tolerance and a search radius for
-vertex edits. Remember the tolerance is in layer units. In our digitizing project, the units are
-in feet. Your results may vary, but something on the order of ?? to ?? should be fine.
-\item A layer based snapping tolerance can be defined coosing \mainmenuopt{Settings} ->
+vertex edits. Remember the tolerance is in layer units. In our digitizing project
+(working with the Alaska dataset), the units are in feet. Your results may vary,
+but something on the order of 300ft should be fine at a scale of 1:10 000
+should be a reasonable setting.
+\item A layer based snapping tolerance can be defined by choosing \mainmenuopt{Settings} ->
\dropmenuopttwo{mActionOptions}{Project Properties\dots}. In the \tab{General} tab, section
\classname{Digitize} you can click on \button{Snapping options\dots} to enable and adjust snapping
mode and tolerance on a layer basis (see Figure~\ref{fig:snappingoptions}).
@@ -844,8 +853,10 @@
\subsubsection{Topological editing}
-Besides layer based snapping options the \tab{General} tab in menu \mainmenuopt{Settings} -> \dropmenuopttwo{mActionOptions}{Project Properties\dots} also provides some topological functionalities.
-In section Digitize you can \checkbox{Enable topological editing} and/or activate
+Besides layer based snapping options the \tab{General} tab in menu
+\mainmenuopt{Settings} -> \dropmenuopttwo{mActionOptions}{Project Properties\dots}
+also provides some topological functionalities.
+In the Digitizing option group you can \checkbox{Enable topological editing} and/or activate
\checkbox{Avoid intersections of new polygons}.
\minisec{Enable topological editing}
@@ -876,29 +887,24 @@
Layer editing is most versatile when used on PostgreSQL/PostGIS data sources.
\begin{Tip}[ht]\caption{\textsc{Data Integrity}}
-\qgistip{Please consider backing up your data source
-before you start editing, and also at regular intervals during editing. QGIS is
-still at a pre-version 1.0 stage, and so may not be able to protect your data in all
-situations.
+\qgistip{It is always a good idea to back up your data source before you start
+editing. While the authors of QGIS have made every effort to preserve the
+integrity of your data, we offer no warranty in this regard.
}
\end{Tip}
\begin{Tip}[ht]\caption{\textsc{Manipulating Attribute data}}
-\qgistip{Currently only PostGIS layers are supported to add or drop attribute
-columns withing this dialog. In further versions of QGIS also other datasources
-will be supported, because this feature was recently implemented in GDAL > 1.6.0
+\qgistip{Currently only PostGIS layers are supported for adding or dropping attribute
+columns within this dialog. In future versions of QGIS, other datasources
+will be supported, because this feature was recently implemented in GDAL/OGR > 1.6.0
}
\end{Tip}
-\begin{Tip}[ht]\caption{\textsc{Editing a Map is Different to Editing an Attribute Table}}
-\qgistip{In this version of QGIS, the \button{Start editing}/\button{Stop editing}
-couplet on the map view acts separately to the \button{Start Editing}/\button{Stop Editing}
-couplet on the attribute table.
-}
-\end{Tip}
+
\begin{Tip}[ht]\caption{\textsc{Save Regularly}}
-\qgistip{Remember to toggle \toolbtntwo{mActionToggleEditing}{Toggle editing} off regularly. This allows you to save your changes thus far,
+\qgistip{Remember to toggle \toolbtntwo{mActionToggleEditing}{Toggle editing} off regularly.
+This allows you to save your recent changes,
and also confirms that your data source can accept all
your changes.
}
@@ -906,7 +912,7 @@
\begin{Tip}[ht]\caption{\textsc{Concurrent Edits}}
\qgistip{This version of QGIS does not track if somebody else is editing a feature at the same time
-as you. The last writer wins.
+as you. The last person to save their edits wins.
}
\end{Tip}
@@ -919,9 +925,8 @@
\begin{Tip}[ht]\caption{\textsc{Vertex Markers}}
\qgistip{
-The current version of QGIS supports several vertex-markers. Currently
-a semi-transparent circle or a
-cross is supported. To change the markers, choose
+The current version of QGIS supports several two kinds of vertex-markers -
+a semi-transparent circle or a cross. To change the marker style, choose
\dropmenuopttwo{mActionOptions}{Options} from the
\mainmenuopt{Settings} menu and click on the \tab{Digitizing} tab and select
the appropriate entry.
@@ -932,16 +937,18 @@
This can be found in the context menu after right clicking on the legend
entry for that layer.\index{Allow Editing}
Alternately, you can use the \index{Toggle Editing}
-\toolbtntwo{mActionToggleEditing}{Toggle editing} button from the toolbar to start or stop the editing mode.\index{editing!icons} Once the layer is in edit mode, markers will appear at the
-vertices.
+\toolbtntwo{mActionToggleEditing}{Toggle editing} button from the toolbar to start
+or stop the editing mode.\index{editing!icons} Once the layer is in edit mode,
+markers will appear at the vertices, and additional tool buttons on the editing
+toolbar will become available.
\minisec{Zooming with the mouse wheel}
While digitizing you can use the mouse wheel to zoom in and out on the map
Place the mouse cursor inside the map area and roll it forward (away from you)
-to zoom in and backwards (towards you) to zoom out. The mouse cursor is the
-center where the zoom occurs. You can customize the behavior of the mouse wheel
-zoom using the \tab{Map tools} tab under the \mainmenuopt{Settings}
+to zoom in and backwards (towards you) to zoom out. The mouse cursor position will
+be the center of the zoomed area of interest. You can customize the behavior
+of the mouse wheel zoom using the \tab{Map tools} tab under the \mainmenuopt{Settings}
>\dropmenuopt{Options} menu.
\minisec{Panning with the arrow keys}
@@ -951,6 +958,10 @@
pan east, left arrow key to pan west, up arrow key to pan north and down arrow
key to pan south.
+You can also use the spacebar to temporarily cause mouse movements to pan
+then map. The PgUp and PgDown keys on your keyboard will cause the map
+display to zoom in or our without interupting your digitising session.
+
You can perform the following editing functions:
\begin{itemize}
@@ -974,7 +985,8 @@
\index{vector layers!adding!feature}
Before you start adding features, use the \toolbtntwo{mActionPan}{pan}
-and \toolbtntwo{mActionZoomIn}{zoom-in}/\toolbtntwo{mActionZoomOut}{zoom-out} tools to first navigate to the area of interest.
+and \toolbtntwo{mActionZoomIn}{zoom-in}/\toolbtntwo{mActionZoomOut}{zoom-out}
+tools to first navigate to the area of interest.
Then you can use the \toolbtntwo{mActionCapturePoint}{Capture point},
\toolbtntwo{mActionCaptureLine}{Capture line} or
@@ -1006,8 +1018,8 @@
\begin{Tip}[ht]\caption{\textsc{Attribute Value Types}}
\qgistip{
At least for shapefile editing the attribue types are validated during the
-entry. Therefor it is not possible to enter a number into the text-column in
-the dialog \dialog{Enter Attribute Values} or vis versa. If you need to do so,
+entry. Because of this, it is not possible to enter a number into the text-column in
+the dialog \dialog{Enter Attribute Values} or vica versa. If you need to do so,
you should edit the attributes in a second step within the \dialog{Attribute
table} dialog.
}
@@ -1128,6 +1140,7 @@
the features are represented in CSV format with the geometry data appearing
in the OGC Well-Known Text (WKT) format.
+
However in this version of QGIS, text features from outside QGIS cannot
be pasted to a layer within QGIS. When would the copy and paste function
come in handy? Well, it turns out that you can edit more than one layer
@@ -1249,8 +1262,8 @@
\index{Query Builder}
The Query Builder allows you to define a subset of a table and display
-it as a layer in QGIS. It can be used for all OGR supported formats, GRASS
-files and PostGIS layers. For example, if you have a \filename{towns} layer with a
+it as a layer in QGIS. It can currently only be used with PostGIS layers.
+For example, if you have a \filename{towns} layer with a
\usertext{population} field you could select only larger towns by entering
\usertext{population > 100000} in the SQL box of the query builder. Figure
\ref{fig:query_builder} shows an example of the query builder populated with
@@ -1287,35 +1300,24 @@
\ref{sec:vectorprops} for more information.}
\end{Tip}
-\subsubsection{Query PostGIS layers}\label{sec:query_builder_postgis}
+\subsection{Select by query}\label{sec:select_by_query}
\index{PostgreSQL!query builder}
\index{PostGIS!query builder}
\index{query builder!PostgreSQL}
\index{query builder!PostGIS}
-To query a loaded PostGIS layer there are two options. The first is to click on the
-button \toolbtntwo{mActionOpenTable}{Open Table} to open the attribute table of the PostGIS layer. Then
+With QGIS it is possible also to select features using a similar query builder
+interface to that used in \ref{sec:query_builder}. In the above section
+the purpose of the query builder is to only show features meeting the
+filter criteria as a 'virtual layer' / subset. The purpose of the select by
+query function is to highlight all features that meet a particular criteria.
+Select by query can be used with all vector data providers.
+
+To do a `select by query' on a loaded layer, click on the
+button \toolbtntwo{mActionOpenTable}{Open Table} to open the attribute table of the layer. Then
click the \button{Advanced...} button at the bottom. This starts the Query Builder
that allows to define a subset of a table and display it as described in Section
\ref{sec:query_builder}.
-The second option to query a PostGIS layer, is to open the \dialog{Layer Properties}
-dialog by double-clicking on the PostGIS layer name in the legend or
-by right-clicking and choosing \dropmenuopt{Properties} from the popup menu. In the tab
-\tab{General} click the \button{Query Builder} button at the bottom.
-\subsubsection{Query OGR formats and GRASS files}\label{sec:query_builder_ogrgrass}
-\index{OGR!query builder}
-\index{GRASS!query builder}
-\index{query builder!OGR}
-\index{query builder!GRASS}
-
-To query a loaded GRASS file or OGR supported format you currently need to click on the
-button \toolbtntwo{mActionOpenTable}{Open Table} to open the corresponding attribute table and click the
-\button{Advanced...} button. This starts the Query Builder and allows to define a
-subset of a table and display it as described in Section \ref{sec:query_builder}.
-
-The second option to start the Query Builder as decribed in Section
-\ref{sec:query_builder_postgis} is currently not supported for OGR and GRASS-layers.
-
\index{vector layers|)}
More information about the QGIS-commit
mailing list