ElizaCollison: Created page with "
=Introduction= In this page we look at the process on assigning elevations to the TUFLOW Zpts that define the elevations in the model. To do this open ArcGIS and open the..."

2023-01-09T01:58:16Z

Created page with "<ol> =Introduction= In this page we look at the process on assigning elevations to the TUFLOW Zpts that define the elevations in the model. To do this open ArcGIS and open the..."

New page

<ol>
=Introduction=
In this page we look at the process on assigning elevations to the TUFLOW Zpts that define the elevations in the model. To do this open ArcGIS and open the DEM, which is provided as part of the '''Module Data''' and is named '''DEM_M01.img'''. Alternatively a layer file the '''DEM_M01.img.lyr''' file can be opened, this opens the same DEM, but with the specific colouring properties shown below.

=Method=
<li>Open the blank Zpt layer '''2d_zpt_M01_5m_002_P.shp''', this was written in the '''TUFLOW\Model\shp\''' directory. The Zpts will appear as a mass of points when zoomed to the full extent.</li>

[[File:Tute M01 Arc Zpts All.png|750px]]
 
<li>Open the ''Arc Toolbox'' (select Window >> Arc Toolbox), from the menu choose ''Spatial Analyst Tools >> Extraction >> Extract Values to Points''.</li> 
<li>Set the input point features to '''2d_zpt_M01_5m_002_P'''</li>
<li>Set the Input raster to '''DEM_M01.img'''</li>
<li>Set the output point features to the '''TUFLOW\model\shp\''' and the file name to '''2d_zpt_M01_5m_003_P.shp'''</li>
<li>Select ''Ok''.</li>
[[File:Tute M01 Arc Toolboxes.png|frame|left|Spatial Analyst Toolboxes]]
 
[[File:Tute M01 Arc Spatial Analyst.png|750px]]
 
A dialogue will be displayed while the extraction is being processed, this may take a few seconds. Once completed, clicking the info tool on one of the updated Zpts within the DEM area should now show an additional data attribute, as per the image below: 
[[File:Tute M01 Arc Zpt Info.png]]
 
ArcGIS has adding a new data column to the which it has inspected from the DEM. The Zpts that are outside of the DEM have been assigned a value of -9,999 values. We need to remove these points, to do this:
<li>Make the newly created '''2d_zpt_M01_5m_003_P.shp''' editable by selecting ''Editor >> Start Editing''.</li>
<li>Select the null values, by using the menu item. ''Selection >> Select by Attributes''. Select where "RASTERVALU" =-9999. Select ''Apply''.</li>
[[File:Tute M01 Arc SelectByAttributes.png]]
 
<li>Delete the selected items by hitting the delete key (or using ''Edit >> Delete'').</li>
<li>Stop editing, by selecting ''Editor >> Stop Editing'' and when prompted save the files.</li>
The Zpts outside the DEM area should now be removed as per the image below, ensure that the '''2d_zpt_M01_5m_002_P'''(superseded) layer is removed or not visible. 
The inspection process created a new data column, however, TUFLOW requires the elevation data to be in the fourth column. There are two ways of overcoming this:
* Updating the fourth (elevation) attribute column to have the values of the newly created (RASTERVALU) attribute.
* Remove the elevation column, so that the RASTERVALU column becomes the fourth column.
We will demonstrate the second option, the first option will results in the same data being stored twice in the shapefile, which will mean bigger file sizes. 
<li>Right click on the '''2d_zpt_M01_5m_003_P.shp''' in the ArcMap Layers control and select ''Open Attribute Table''.
<li>Select the '''ELEVATION'' field, right-click on the label and select ''Delete Field''.</li>
[[File:Tute M01 ArcMap remove field.png|frame|none|Deleting the Elevation Field in ArcMap]]
<li>When prompted select ''Yes''</li>
[[File:Tute M01 ArcMap Remove Field Confirm.png|frame|none|Confirm Delete Field]]
 
To confirm the delete was successful, click the info tool on one of the Zpts, the elevation field should now been removed: 
[[File:Tute M01 Arc Zpt Info2.png|none|frame|2d_Zpt fields after removal of "Elevation" field.]]
 
<li>Save the current TGC file as '''M01_5m_003.tgc'''. Comment out or delete the Write MI and Stop lines entered previously (these are no longer needed).</li>

<li>Add the following lines to the TGC file and save.</li>
<tt>Set Zpts </tt> <tt>== 75</tt> 
<tt>Read RowCol Zpts </tt> <tt>== </tt> <tt>..\model\shp\2d_zpt_M01_5m_003_P.dbf</tt> 
== Conclusion ==
The Zpts have been inspected from the DEM, the geometry control file (.tgc) updated to use the inspected Zpts. Please return to the tutorial model module 1 page where the next step is to [[Module1_test_Archive#Define_Preliminary_Active_and_Inactive_Areas_of_the_2D_Domain|define the active areas]].
</ol>

Tute M01 Inspect Zpts Arc Archive - Revision history

ElizaCollison: Created page with " =Introduction= In this page we look at the process on assigning elevations to the TUFLOW Zpts that define the elevations in the model. To do this open ArcGIS and open the..."

ElizaCollison: Created page with "
=Introduction= In this page we look at the process on assigning elevations to the TUFLOW Zpts that define the elevations in the model. To do this open ArcGIS and open the..."