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SurView TutorialPicking features |
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The 'hotspot' of SurView's cursor
is the end of the 'stinger' on the nose of the aircraft.
The cursor is a 'replica' of the 'Skyvan' aircraft (manufactured by Short Brothers & Harland). The Skyvan was owned by the Geological Survey of Canada (Canadian registration CF-GSC) and was in continuous use for airborne gamma-ray spectrometry research & development from 1968 to 1995.
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![]() right mouse button configured to pick polygons |
You can query polygons, polylines, and points by 'picking' them with the right mouse button, but this will only work if the file has been enabled for picking the data preparer. Not all features can be picked. It's common to specify no pick action for rivers, lakes, boundaries - data types for which little or no useful information is available.
Depending on how the files have been set up by the data author, in response to a click, SurView might do any of the following pick actions:
Pick mode
In some GIS packages, a file or layer is activated for picking. In
SurView, all files configured for picking are always active, but you can
set a pick mode for picking:
with the right mouse button. If only one of these file types is being viewed, then the right mouse button will usually configure itself automatically to pick the appropriate type of item. However, if you are displaying more than one of these types of features, then you must use the Pick | Right mouse button pick mode menu item to configure the right mouse button for picking one of the three types of objects and to adjust the pick tolerance (for lines and points).
Pick tolerance
Note that the pick tolerance for polylines is adjusted automatically
each time the scale of the picture changes (the computed value is about 1%
of the current view width), but you may have to adjust the value in order
to pick a polyline correctly.
Check all polygons/stop on first polygon found
SurView uses a 'point in polygon' test that can be quite slow,
despite it being optimized, if there are a lot of polygons. To speed
up the search, SurView assumes that most of the time, there will only
be one file of polygons that can be picked. It also assumes that those
polygons are mutually exclusive, i.e. that they don't overlap. Accordingly,
the default pick mode for polygons is stop on first polygon found.
If there are several files or if there are overlapping polygons, this
should be changed to check all polygons. SurView will then check
every polygon in every file. If the 'point in polygon' test finds more
than one polygon, a popup menu will display the choices and one of
them can be selected.
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SLD files contain multivariable airborne or ground Survey Line Data. SLD files can be used to draw flight lines & profile maps in the map view. A flight line can be picked with the right mouse button or by selecting the flight line from the list provided using the Profiles | Choose line by name menu item. After confirming the picked line selection, the stacked profile data for that line will be drawn in a new, separate window from the map view. More detail is provided in the SLD section.
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When picking points or arcs SurView will use the pick tolerance to find all points or arcs within the indicated distance from the pick point. For polygons, SurView finds all polygons (or the first one) that contains the pick point. If there is more than one feature that satisfies the picking criteria, the choices are listed in a popup menu that always appears in the upper left corner of the SurView window.
Once the selection of the feature has been made (either as a unique feature or picked from the list of possible features). SurView retrieves the list of pick actions enabled by the data preparer. If there is one pick action, it is invoked. If there are multiple pick actions for the point, they are listed in a popup menu. The location of the menu showing the available pick actions is controlled by the Pick | Pick action menu pops up at pick point option. If not enabled, the menu appears in the upper left corner of the SurView map window, otherwise it appears at the pick point on the map. Note that this does not affect the location of the popup menu of possible features, which always appears in the upper left corner of the map window.
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![]() DBF record for picked feature |
Most of the pick actions are relatively simple, but SurView has several ways to view and explore linked DBF files that are attached to a point, line or polygon feature.
The dialog box shows the record for the picked feature from the DBF file that is associated with the spatial data file:
If the data preparer has fully configured the DBF files, a title
or description of the DBF file will appear at the top.
If the data preparer has provided descriptions of the DBF
fields, as each field in the dialog box is selected (highlighted),
a description of the field will appear directly below the list.
The contents of the field will also appear in a larger area below
that for easier viewing. You can also scroll the list left/right
to view the information in long fields.
The complete set of descriptions can be displayed by clicking the Describe all button:
The data preparer has an option to suppress some fields from the
DBF record display. These are usually uninteresting fields such
as polygon id, area, centroid etc. Enabling All fields
allows all of the fields to be displayed.
If there is more than 1 record that describes the current feature,
the top of the list will indicate that (#n of m selected)
and the << & >> buttons will be enabled. This is
usually not the case for the primary data record, but for a
subsequent linked DBF file of references (for example), it
is common.
If the data preparer has configured the files with 1 or more
subsequent pick actions that can be activated from this DBF
record dialog box, those actions will be made available from
the More info button. If there is only 1 action, a menu
may or may not appear (option), otherwise a popup list of
actions will appear. Choosing an item will result in the action
being performed.
The Edit button is used to edit the current field that is
selected in the list. The contents are copied down to an editing
area. The Edit all button is used to cycle through all of
the fields to save clicking Edit each time. Of course,
if the DBF file is read-only (as it would be on a CD), these buttons
are disabled.
These buttons are used to copy or append the complete list of
data to the Windows clipboard, after which it may be pasted into
an application like Notepad for printing or saving in an alternate
form.
If the DBF file is linked to other DBF tables (files) they
will appear in a dropdown list at the bottom of the dialog box.
Select a table and click Display to view the information
linked to the current record - the search may yield 0, 1 or
more records.
The complete set of information can also be viewed by selecting All and clicking the Display button. This will follow the links to all of the secondary DBF files and display the information in a hierarchical list.
![]() select a linked table... |
![]() ...click Display to see the record(s)... |
![]() ...or click Display All to see all of the data |
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