Raster Alignment - QGIS Documentation [PDF]

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"

QGIS User Guide Release 2.14

QGIS Project

August 08, 2017

Contents

1

Preâmbulo

1

2

Convenções 2.1 Convenções GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Convenções de Texto ou Teclado . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Instruções específicas da plataforma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 3 3 4

3

Prefácio

5

4

Características 4.1 Visualização de dados . . . . . . . . . . . . . 4.2 Exploração de dados e compositores de mapas 4.3 Criar, editar, gerir e exportar dados . . . . . . 4.4 Analyze imagerelpath="images/test_image.jpg" projectpath=qgis.core.QgsProject.instance().fileName() import os.path path=os.path.dirname(str(projectpath)) if projectpath != ’’ else None image=os.path.join(path, imagerelpath) import subprocess subprocess.Popen( [command, image ] )

Another Python action example is the one that allows us to add new layers to the project. For instance, the following examples will add to the project respectively a vector and a raster. The names of the files to be added to the project and the names to be given to the layers are , group=’Custom’) def myfunc(value1, value2, feature, parent): pass

The short example creates a function ‘myfunc’ that will give you a function with two values. When using the args=’auto’ function argument the number of function arguments required will be calculated by the number of arguments the function has been defined with in Python (minus 2 - feature, and parent). This function then can be used with the following expression: myfunc(’test1’, ’test2’)

Your function will be implemented in the Custom functions group of the Expression tab after using the Run Script button. Further information about creating Python code can be found in the PyQGIS-Developer-Cookbook. The function editor is not only limited to working with the field calculator, it can be found whenever you work with expressions.

12.5 Working with the Attribute Table The attribute table displays features of a selected layer. Each row in the table represents one map feature, and each column contains a particular piece of information about the feature. Features in the table can be searched, selected, moved or even edited. To open the attribute table for a vector layer, make the layer active by clicking on it in the map legend area. Then, from the main Layer menu, choose

Open Attribute Table. It is also possible to right click on the layer and

Open Attribute Table from the drop-down menu, and to click on the choose in the Attributes toolbar.

Open Attribute Table button

This will open a new window that displays the feature attributes for the layer (figure_attributes_1). The number of features and the number of selected features are shown in the attribute table title.

Figure 12.60: Attribute Table for regions layer The buttons at the top of the attribute table window provide the following functionality: 12.5. Working with the Attribute Table

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Toggle editing mode



Save Edits



Reload the table



Add feature



Delete selected features



Select features using an Expression



Select all



Invert selection



Unselect all



Move selected to top



Pan map to the selected rows



Zoom map to the selected rows



Copy selected rows to clipboard



Paste from clipboard to a new row



Delete Column



New Column



Open field calculator

to enable editing functionalities (also with Ctrl+e)

(also with Ctrl+s)

(also with Ctrl+d)

(also with Ctrl+a) (also with Ctrl+r)

(also with Ctrl+u) (also with Ctrl+t) (also with Ctrl+p) (also with Ctrl+j) (also with Ctrl+c) (also with Ctrl+v)

for PostGIS layers and for OGR layers with GDAL version >= 1.9 (also with Ctrl+l)

for PostGIS layers and for OGR layers with GDAL version >= 1.6 (also with Ctrl+w) (also with Ctrl+i)

Below these buttons is the Field Calculator bar (enabled only in editing mode), which allows calculations to be quickly applied to either all or selected features attributes in the table. This bar uses the same expressions as the Field Calculator

(see Field Calculator).

Tip: Skip WKT geometry Copy selected rows to clipboard button. If you want to use attribute > ...

The client has now the information to request a print output:

http://myserver.com/cgi/qgis_mapserv.fcgi?...&REQUEST=GetPrint&TEMPLATE=Druckzusammenstellung 1&ma

Parameters in the GetPrint request are: • :EXTENT gives the extent for a composer map as xmin,ymin,xmax,ymax. • :ROTATION map rotation in degrees • :GRID_INTERVAL_X, :GRID_INTERVAL_Y Grid line density for a composer map in x- and y-direction • :SCALE Sets a mapscale to a composer map. This is useful to ensure scale based visibility of layers and labels even if client and server may have different algorithms to calculate the scale denominator • :LAYERS, :STYLES possibility to give layer and styles list for composer map (useful in case of overview maps which should have only a subset of layers) GetLegendGraphics request Several additional parameters are available to change the size of the legend elements: • BOXSPACE space between legend frame and content (mm) • LAYERSPACE versical space between layers (mm) • LAYERTITLESPACE vertical space between layer title and items following (mm) • SYMBOLSPACE vertical space between symbol and item following (mm) • ICONLABELSPACE horizontal space between symbol and label text (mm) • SYMBOLWIDTH width of the symbol preview (mm) • SYMBOLHEIGHT height of the symbol preview (mm) These parameters change the font properties for layer titles and item labels: • LAYERFONTFAMILY / ITEMFONTFAMILY font family for layer title / item text • LAYERFONTBOLD / ITEMFONTBOLD ‘TRUE’ to use a bold font • LAYERFONTSIZE / ITEMFONTSIZE Font size in point • LAYERFONTITALIC / ITEMFONTITALIC ‘TRUE’ to use italic font • LAYERFONTCOLOR / ITEMFONTCOLOR Hex color code (e.g. #FF0000 for red) • LAYERTITLE / RULELABEL (from QGIS 2.4) set them to ‘FALSE’ to get only the legend graphics without labels Contest based legend. These parameters let the client request a legend showing only the symbols for the features falling into the requested area: • BBOX the geographical area for which the legend should be built • CRS / SRS the coordinate reference system adopted to define the BBOX coordinates

14.2. QGIS as OGC , ATTRS{idProduct}=="0003", MODE="666"

Depois disto é necessário ter a certeza que o módulo kernel do garmin_gps não está carregado rmmod garmin_gps

e de seguida pode usar as Ferramentas GPS. Infelizmente, parece existir um bug #7182 e normalmente o QGIS pára várias vezes antes da operação trabalhar bem. BTGP-38KM encoding="UTF-8"?>

The parser reads this definition and creates a new tab inside the Toolbox when you select the module. A more detailed description for adding new modules, changing a module’s group, etc., can be found on the QGIS wiki at http://hub.qgis.org/projects/quantum-gis/wiki/Adding_New_Tools_to_the_GRASS_Toolbox.

260

Chapter 17. Integração GRASS SIG

CHAPTER 18

QGIS processing framework

18.1 Introdução This chapter introduces the QGIS processing framework, a geoprocessing environment that can be used to call native and third-party algorithms from QGIS, making your spatial analysis tasks more productive and easy to accomplish. In the following sections, we will review how to use the graphical elements of this framework and make the most out of each one of them. There are four basic elements in the framework GUI, which are used to run algorithms for different purposes. Choosing one tool or another will depend on the kind of analysis that is to be performed and the particular characteristics of each user and project. All of them (except for the batch processing interface, which is called from the toolbox or the algorithm execution dialog, as we will see) can be accessed from the Processing menu item. (You will see more than four entries. The remaining ones are not used to execute algorithms and will be explained later in this chapter.) • A caixa de ferramentas. O elemento principal do GUI, é usado para executar um algoritmo único ou correr um processo batch baseado nesse algoritmo. • The graphical modeler. Several algorithms can be combined graphically using the modeler to define a workflow, creating a single process that involves several subprocesses. • The history manager. All actions performed using any of the aforementioned elements are stored in a history file and can be later easily reproduced using the history manager. • A interface de processamento batch. Esta interface permite que possa executar processos batch e automaticamente a execução de um único algoritmo num múltiplo conjunto de dados. In the following sections, we will review each one of these elements in detail.

18.2 A caixa de ferramentas The Toolbox is the main element of the processing GUI, and the one that you are more likely to use in your daily work. It shows the list of all available algorithms grouped in different blocks, and it is the access point to run them, whether as a single process or as a batch process involving several executions of the same algorithm on different sets of inputs. The toolbox contains all the available algorithms, divided into so-called “Providers”. Providers can be (de)activated in the settings dialog. A label in the bottom part of the toolbox will remind you of that whenever there are inactive providers. Use the link in the label to open the settings window and set up providers. We will discuss the settings dialog later in this manual. By default only, providers that do not rely on third-party applications (that is, those that only require QGIS elements to be run) are active. ALgorithms requiring external applications might need additional configuration. Configuring providers is explained in a later chapter in this manual. 261

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Figure 18.1: Processing Toolbox

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Figure 18.2: Processing Modeler

Figure 18.3: Processing History

18.2. A caixa de ferramentas

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Figure 18.4: Batch Processing interface In the upper part of the toolbox, you will find a text box. To reduce the number of algorithms shown in the toolbox and make it easier to find the one you need, you can enter any word or phrase on the text box. Notice that, as you type, the number of algorithms in the toolbox is reduced to just those that contain the text you have entered in their names. If there are algorithms that match your search but belong to a provider that is not active, an additional label will be shown in the lower part of the toolbox. If you click on the link in that label, the list of algorithms will also include those from inactive providers, which will be shown in light gray. A link to active each inactive provider is also shown. Para executar um algoritmo, faça duplo clique no seu nome na caixa de ferramentas.

18.2.1 O diálogo do algoritmo Once you double-click on the name of the algorithm that you want to execute, a dialog similar to that in the figure below is shown (in this case, the dialog corresponds to the ‘Polygon centroids’ algorithm). This dialog is used to set the input values that the algorithm needs to be executed. It shows a list of input values and configuration parameters to be set. It of course has a different content, depending on the requirements of the algorithm to be executed, and is created automatically based on those requirements. Although the number and type of parameters depend on the characteristics of the algorithm, the structure is similar for all of them. The parameters found in the table can be of one of the following types. • A raster layer, to select from a list of all such layers available (currently opened) in QGIS. The selector contains as well a button on its right-hand side, to let you select filenames that represent layers currently not loaded in QGIS. • A vector layer, to select from a list of all vector layers available in QGIS. Layers not loaded in QGIS can be selected as well, as in the case of raster layers, but only if the algorithm does not require a table field selected from the attributes table of the layer. In that case, only opened layers can be selected, since they need to be open so as to retrieve the list of field names available. Irá ver um botão por cada seleccionador de camada vectorial, como é exibido na figura em baixo. If the algorithm contains several of them, you will be able to toggle just one of them. If the button corresponding to a vector input is toggled, the algorithm will be executed iteratively on each one of its features, instead of just once

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Figure 18.5: Processing Toolbox

18.2. A caixa de ferramentas

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Figure 18.6: Processing Toolbox showing search results

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Figure 18.7: Processing Toolbox showing search results

18.2. A caixa de ferramentas

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Figure 18.8: Parameters Dialog

Figure 18.9: Vector iterator button

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for the whole layer, producing as many outputs as times the algorithm is executed. This allows for automating the process when all features in a layer have to be processed separately. • A table, to select from a list of all available in QGIS. Non-spatial tables are loaded into QGIS like vector layers, and in fact they are treated as such by the program. Currently, the list of available tables that you will see when executing an algorithm that needs one of them is restricted to tables coming from files in dBase (.dbf) or Comma-Separated Values (.csv) formats. • Uma opção, a escolher de uma lista de selecção de uma lista de opções possíveis. • A numerical value, to be introduced in a text box. You will find a button by its side. Clicking on it, you will see a dialog that allows you to enter a mathematical expression, so you can use it as a handy calculator. Some useful variables related to ) output=SpatialPoints)

A variável polygon já contém o objecto SpatialPolygons?> Import all photograph points This command will import all of the encoding="UTF-8"?>

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