Transcript Global Mapper - Alberta Ministry of Transportation

Global Mapper
Hydrotechnical Data Extraction
Global Mapper – Hydrotechnical Data Extraction
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Overview
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Projection
Drainage Area
Stream Profile
XS Data
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Projection
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Most measurement applications in Global Mapper look and work
better if the projection is set to a Transverse Mercator projection,
where one metre will look the same in both the North-South and
East-West directions.
Options for Alberta include UTM Zone 11 (W of 114deg), UTM
Zone 12 (E of 114 deg), 10TM (entire province) or 3TM (smaller
areas, e.g. survey).
Different GIS data files may store data in different projection
systems, but Global Mapper will convert and display in the
selected projection.
To select projection – Tools: Configuration (or Configuration
button), select “Projection Tab”, pick from list for UTM, “Load From
File” for 10TM or 3TM (point to root of GIS folder, pick PRJ file).
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Drainage Area (DA) - Overview
1.
2.
3.
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6.
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8.
Locate Map Sheet number for Site
Open Global Mapper and set projection to a TM type
Load GIS Data - DEM, Streams, and Bridges (photos, lidar etc.)
Zoom to extents of DA
Generate Contours
Draw DA boundary
Modify DA, if necessary
Large DA – Use Multiple Polygons
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1. Locate Map Sheet Number
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Use HIS to locate Map Sheet Number for Bridge Site
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2. Open Global Mapper
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Open Global Mapper and Set Projection to TM type
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3a. Load GIS Data - DEM
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Drag and drop DEM file from GIS folder (DEM\83B\83B16.bil)
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3b. Load GIS Data - Streams
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Drag and drop Stream file from GIS folder (Streams\83B Streams.zip)
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3c. Load GIS Data - Bridges
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Drag and drop Bridges file from GIS folder (Bridges.zip)
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4. Zoom to Extents of DA
a)
b)
c)
d)
Find selected site (centre)
Zoom in/out to extent of DA – use DEM and Streams as guide
Add additional DEM and Streams files as necessary
Refine zoom, if necessary, with zoom tool
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4a. Find Bridge Site
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Search : “Search By Name”
Enter Site Number
Double click on number on list
Click OK - bridge will now be in the centre of the screen
Type Here
Double Click
Here
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4b. Zoom In/Out
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Use Zoom, Zoom In, Zoom Out, and Pan tools to zoom to visible extents of
DA, with DEM and streams as rough guide.
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4c. Add more DEM, Streams
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If necessary, add additional DEM and Streams layers to cover the entire DA
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4d. Refine Zoom
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If necessary, add additional DEM and Streams layers to cover the entire DA
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5. Generate Contours
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File : Generate Contours
Select this to limit
contouring to
screen area,
much faster than
“all loaded data”
Enter Contour
Interval e.g. 10m
for steep areas,
2m for flat areas
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5. Generate Contours
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6. Draw DA Boundary
a)
b)
Select Measure Tool
Start clicking at outlet point, click points along DA boundary :
i.
ii.
iii.
iv.
c)
d)
Follow ridge lines in the contours
Include all stream tributaries
Cross contours on square
hold down “Alt” key to avoid snapping to elements
Note DA on status bar before closing polygon
Close polygon by right clicking on outlet point (select “Save
Measurement” to keep measurement as area or line)
i.
ii.
Area – retains measurement but shades polygon display and can
interfere with selecting features
Line – does not retain measurement, but can be converted to an
Area feature later, if necessary
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6b. Draw DA Boundary
Measurement in
progress
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6c. Draw DA Boundary
Outlet Point
Area
Measurement
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7. Modify DA Boundary
a)
b)
c)
d)
Zoom to area of interest
Turn on “Render Vertices” – Shift + V
Select point to be moved
Right-click on point and select “Move Selected Vertex” (or Alt +
click)
Move point to desired location
Points can also be inserted and deleted
e)
f)
i.
ii.
Area – retains measurement but shades polygon display and can
interfere with selecting features
Line – does not retain measurement, but can be converted to an
Area feature later, if necessary
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7. Modify DA Boundary
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If edited polygon is an Area shape, the area measurement will be
automatically updated (double click with digitizer tool or click with
Info tool to see updated value).
If polygon is a Line shape, the following steps are required to see
the updated area:
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a)
b)
c)
d)
Select Line
Right click and select “Create New Area Feature from Selected Line”
Right click on new Area shape and select “Add/Update the Measure
Attributes of Selected Feature”
Read area value the same way as for an Area shape (see above)
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7. Modify DA Boundary
Selected
Vertex
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7. Modify DA Boundary
Points
moved,
inserted
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8. Multiple Polygons
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For large DA’s that can’t be easily analysed on one screen,
multiple polygons can be used as follows:
a)
b)
c)
d)
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Identify recognizable points for which incremental areas can be
assessed on one screen at a reasonable level of zoom (e.g. bridges,
confluences, other features on imagery…)
Measure the DA for the most upstream point.
Add an incremental measurement for each subsequent downstream
point, using previous DA boundary as a guide for common
boundaries (don’t hold down Alt key to snap)
Sum DA’s for all polygons to get total
A similar process can be used to break basins into sub-basins for
qualitative assessment of runoff or quantitative routing
calculations.
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8. Multiple Polygons
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Stream Profile - Overview
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6.
Starting with file for DA, prepare for stream selection
Select all arcs that make up the stream
Combine Arcs to form one line
Generate Profile for line
Calculate slope for desired location
(Optional - HIS Only) Import profile into HIS
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1. Prepare for Stream Selection
1.
2.
Open Overlay Control Center
Un-check any vector layers that may affect stream arc selection:
a.
b.
c.
3.
especially “Generated Contours” layers
also “User Created Features” layer to hide DA polygons
can leave bridge points on as they won’t interfere with line selection
Zoom to extent of stream to be profiled
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1. Prepare for Stream Selection
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2. Select Stream Arcs - Unnamed
1.
Unnamed streams – add arcs technique:
a.
b.
c.
2.
Select upstream arc using digitizer tool
Add the next downstream arc (CTRL + click)
Continue to end of stream
Unnamed streams – remove arcs technique:
a.
b.
Select all vectors in stream network by dragging a box with the
digitizer tool
Remove arcs that are not on the main stream (SHFT + click)
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2. Select Stream Arcs - Unnamed
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2. Select Stream Arcs - Named
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Search – Search By Name – enter part of stream name
In list, click on 1st match item, SHFT + click on last match item
Click “Edit Selected”, “Create New Type”, enter name (OK-OKClose)
Configuration – Vector Display Tab – Filter Lines – Clear All and
click check box by new feature (OK-OK)
Draw box around all remaining contiguous arcs on screen
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2. Stream Selection - Named
Enter start of
Stream name
Click here to
set type
Click here to
create new type
Select all
matches
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2. Stream Selection - Named
Click here to turn
off all lines
Click here to turn
off other lines
Click here to turn
on new line type
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2. Stream Selection - Named
Selected
Stream
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3. Combine Selected Arcs
1.
2.
Right Click on selected arcs and click on “Combine Selected Line
Features” and “OK”
De-select and re-select line to make sure all arcs were combined.
If not, turn on “Render Vertices (SHFT + V)” and zoom in at points
where the line combination failed and fix the problem by:
a.
b.
3.
If lines are not contiguous - connect the lines with a short arc or snap
move one vertex on top of the other
If the wrong arc was selected (such as a tributary), break that line at
the confluence point and re-select and combine on the correct line.
Once lines are combined, they will be moved from the active
Streams layer to the “User Created Feature” layer, and may
disappear if this layer is hidden.
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4. Generate Profile
1.
2.
Right Click on the combined line segment and click on “Generate
Path Profile Along Line”. This option will not appear if a DTM
layer is not turned on.
A plot of the profile of the line will appear
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4. Generate Profile
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5. Calculate Slope at Point
1.
Estimate Slope from Plot
a.
b.
c.
2.
Identify approximate station of point of interest along profile (measure
if necessary)
Identify which profile section applies to this point (if point is near cusp
of 2 significantly different slope sections, more work will be required
to estimate slope.
Identify the coordinates of 2 points on the appropriate slope section
and calculate slope as dy/dx.
Export Data to Spreadsheet and calculate Slope
a.
b.
c.
From Plot window, select File – Save Distance/Elevation File
Open saved file in spreadsheet
Plot as necessary and calculate slope between 2 points defining
slope for point of interest
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6. Import to HIS
1.
Export Data to x,y,z text file
a.
b.
c.
2.
Import into “Stream Slopes.mdb” File
a.
b.
3.
Change projection temporarily to Geographic
From Plot window, select File – Save XYZ File as xxxx.xyz where
xxxx = unique ID code for this stream used by HIS
Save XYZ files for other streams as necessary
Open “Add Prof to DB” tool
Enter stream ID numbers to add and point to path of exported files
and click “Go”
The stream profile will now be available within HIS, allowing
precise locating of the bridge on the profile and the use of the
built-in slope calculation tool.
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XS Data
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2.
DTM – XS Extraction
Imagery Measurement
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1. DTM - XS Extraction
1.
Open DTM layer:
a.
b.
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3.
Identify XS locations that appear to be typical of the channel (see
Hydrotechnical Design Guidelines)
View Elevation Profile:
a.
b.
4.
100m spacing DTM generally insufficient for XS (B,h,T)
Better - LIDAR, Photogrammetry, 3D surfaces from survey points
Use 3D Path Tool to draw the line to be profiled (good for quick views,
but line will not be saved)
Use Measure Tool or Digitizer Tool to draw line and save as line when
done. Right click on saved line and select “Generate Path Profile
Along Line”
Characterize typical values for B, h, and T based on the profile
plots at selected sections (export to text file for use in other tools,
if necessary).
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1. DTM – XS Extraction
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1. DTM – XS Extraction
LIDAR
100m DTM
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1. DTM – XS Extraction
LIDAR
100m DTM
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2. Imagery Measurement
1.
Open Imagery layer:
a.
b.
2.
3.
Identify XS locations that appear to be typical of the channel (see
Hydrotechnical Design Guidelines)
Use Measure Tool to measure channel dimensions at selected
locations:
1.
2.
3.
4.
Satellite imagery OK for large rivers but too grainy (2.5m pixels) for
small channels when zoomed in
Georeferenced airphotos allow for more precise scaling
B - based largely on water surface width or width between vegetation
T – based on visual clues as to top of bank (apparent elevation
change, change in vegetation)
h – difficult to assess from imagery. Visual comparison with other
sites where ‘h’ is known will help to set limits on bank height.
Characterize typical values for B and T based on the
measurements
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2. Imagery Measurement
Satellite Image
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2. Imagery Measurement
Georeferenced
Airphoto
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QUESTIONS?
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