Lesson 5. Input of altitude data
Step 1. Attribution of contour lines to different layers and structure
check-up
We shall distribute contours among different layers for automatic input of Z values, i.e.
separate intermediate (ordinary) and index (thick) isolines. It will enable us to specify Z
increment and line appearance separately for these two kinds of contours.
1.Click Ctrl+L to open
Layer Manager.
2.Click the mouse right button in the
Vector Layers zone of the dialog box
to open context menu. Select Create
Layer in it.
3.Input the new layer name - Thick
lines.
4.Close Layer Manager.
5.Select index lines with Group Editor
and press “S” key (Cyclic Layer
Changing) to attribute them to the
new-created layer.
6.Review the entire project. Contour
line attribution to different layers
helps to see the structure of material
better at Z data input.
7.Check the structure of relief
contours. Select Relief Processing
-> Z Structure Checkup in Utilities
menu.
8.Switch on the Check twoness of
contour joining to relief elements
option
Input of altitude data
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The program will check if all
contours connected with lines of
special relief elements (land forms)
are paired.
Specify Land forms layer for lines of
relief elements.
9.Switch on the Check twoness of
contour joining to hydrography
polygons option.
The program will check if all
contours connected with polygons of
water bodies are paired.
Specify Hydrography_pol layer for
polygons of hydrographic objects.
10.Switch on the Check sequence of
contour types and levels along linear
rivers option.
The program will check the order of
contours at crossings with rivers.
Specify Hydrography_lin layer for
river lines.
11.Switch on the Find spiral contours
option. The program will analyze
contour shape and mark supposedly
helical lines as errors.
12.Click Start.
The program executes a check of
contour structure based on two
criteria: connections with land form
lines should be paired and crossings
with river lines should be ordered
correctly.
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2. Automatic input of altitude data
It is necessary to specify the layers of contour lines in the “Z Parameters“ dialog box
for automatic input of Z data with Z-input tool. The dialog box comprises three pages:
General, Types, and View.
1.Select Z Parameters in Service
menu.
2.Specify Relief, Thick Lines layers
of relief contours on General
page.
3.Select layer for Contour type is
designated by... option.
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4.Select the layers of altitude marks
- Geodetic base_pnt.
5.Specify Z range:
Minimal value of Z - 200.00;
Maximal value of Z - 2000.00.
6.Specify 0 for Baze value (it may be
any altitude value permitted for
index contours). It will be used for
automatic input of Z values and
check of existing ones.
7.Specify 0 for Null value (default
altitude value of all contours
before Z input).
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8.Click ОК.
9.Input line representation settings
for Intermediate and Index
contour types on the Types page.
10.Specify Thick lines layer for
index lines and Relief layer for
intermediate ones.
Input of altitude data
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11.Specify the Step of Z change:
intermediate lines - 40.00;
index lines - 200.00.
12.Specify line width:
intermediate lines - 0.05 мм;
index lines - 0.10 мм.
13.Click ОК.
14.Adjust distribution of colors in the
range of permitted Z values on the
View page.
There are color indicators (sliders) in the left zone of the dialog box that allow you to
choose colors for individual elevation values. You may capture any slider with the
mouse left button and shift it along the color range. Left click between two sliders creates
a new slider, right click on a slider deletes it.
15.Input representation settings for
Z labels - select Yes for Color by Z
value and input Label text height =
0,2 mm.
16.Input representation settings for
elevation marks - select Yes for
Color by Z value
17.Input representation settings for
objects without Z values - we shall
use special color and special width
to make them prominent.
Select white color for objects
without Z values.
18.Click ОК.
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19.Select Z-tool in Tools menu (Alt+Z
hot key). The program will start
the View Z mode when object color
depends on the object’s Z value.
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20.Tick off Geodetic base_pnt layer of
elevation marks on the Point Layer
Setup page.
21.Switch on Use rivers option and
select Hydrography_lin. layer of
river lines.
22.Switch on Consider following layers
as barriers option on the Barrier
and Boundary Layers Setup page.
Tick off Land form layer as objects
attributed to this layer may break
the order and the route of isolines. 24
23.Switch on Consider specified layer
as a boundary option and select
Frame.
24.Switch on Consider following layers
as gaps option on the Gap Layers
Setup page.
Tick off Hydrography_pоl layer of
polygonal objects that may break
contours.
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25.Switch on Consider all local peaks
as hills option on the Additional
Parameters page.
26.Click Finish.
Input of altitude data
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Step 3. Manual Z input and altitude checkup
Z-input tool may be opened from Tools menu, or Special tool bar, or by Alt+Z key
combination. It has four modes (Shift for mode change) intended for different situations:
1.
Contour Crossing mode is convenient in case of close-packed groups of contours.
To assign Z-values to several neighboring polylines, “cross” them with the mouse. “To
cross” means to click the mouse left button on both sides of an isoline beam (see Video
lesson 5). Successive Z values will be assigned to the crossed polylines in compliance with
the step of its change specified in the Z Parameters -> Types dialog box. To refuse from
the operation after the first point specifying, press Esc or click the right button of the
mouse.
Z-values decrease in the crossed line beam if the second point is clicked with the right
button or at Shift key pressed, otherwise they increase. Arrows on the crossing line
indicate current direction of altitude increase.
Generally, initial value in the beam should be specified in the From Z= field of the
Parameter bar but if the first point of the crossing polyline is selected in a contour
that has a Z value already, this value becomes one to start from. Besides, you may use
a point (elevation mark) - its Z value will be approximated in accordance with the
specified Z increment for isolines.
You may continue Z input proceeding from Z-values already assigned to contours and
points until the whole map is processed.
2.
Along River Lines mode.
Elevation values will be successively set to all polylines crossing a user-specified river
(that already exists in the project). Direction of Z change is reverse to the reference line
direction, i.e. Z values decrease from the start point of the line (river head) to its end
(river mouth).
The operation starts from the first polyline, which already has a Z value. So, there
should be at least one contour with Z value before you start this mode, otherwise you
will see an error message.
3.
Pointing mode.
Although the simplest, this mode is often in use. When it is on, click inside a close
contour to assign it the current altitude value. The method is convenient for numerous
small contours having the same altitude (e.g., a plane with low hills). On the other hand,
it may be better sometimes to select such contours by the frame of the Group Editor and
assign a Z-value to all of them at once.
Right click – to “take” the value of the specified contour (to make it current); left click –
to input the value.
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4.
Magic Wand mode.
This mode resembles the previous one as it also takes 1 click in it to assign altitude to 1
contour, but it is a little more advanced.
The program analyses Z-values of near-by isolines when you click a contour and assigns
it an altitude value automatically if these data are sufficient. Calculation results depend
on the mouse button you have pressed – the contour will be considered as a high after
left click and as a depression after right click.
1.Elevation values are assigned.
We shall check them now.
Select Relief Processing -> Z Checkup
in Utilities menu.
2.Switch on the Check contour type
alternation option to verify the
sequence of intermediate and index
contours.
3.Switch on the Check up contours
using streamways from layers option
and select Hydrography_lin layer.
4.Switch on the Check up contours
against elevation points from layers
option and select Geodetic_pnt
layer.
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5.Switch on the Use barriers and
boundaries from layers option and
select Frame; Land forms layers.
6.Error marks are line segments that
connect objects with an erroneous
sequence of elevation changes.
Input of altitude data
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7.Hydrographic objects are closely
connected with relief. That’s why we
can input river line direction on the
base of elevation contours.
Select Relief Processing -> Orient
Rivers in Utilities menu.
8.Select the layer of river lines Hydrography_lin.
9.In the Mark... option tick off:
...redirected rivers - i.e. to mark
a river line if its direction was
changed;
... discovered Z order errors incorrect change of Z-values;
... river nodes with more than one
run outs (crotches) - nodes with
several outgoing river channels;
... river nodes with more than three
degree - nodes of high orders.
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