GeoTalks Express – Session 3 Questions & Answers

The third of Blue Marble’s GeoTalks Express online webinar series, entitled So you think you know Global Mapper, was conducted on April 29th, 2020. During the live session, numerous questions were submitted to the presenters. The following is a list of these questions and the answers provided by Blue Marble’s technical support team.

 

Is there a tool for pan-sharpening?

Yes, Global Mapper has a tool for pan sharpening. The Pan-Sharpen Imagery tool can be found under the Analysis menu. Additional information on the pan-sharpen tool can be found here in the Global Mapper knowledge base

 

Can you import a line vector and generate the profiles?

Yes, you can select a vector line feature in Global Mapper and open a path profile along that line. The line does not need to be 3D as the path profile view will sample and display the elevation grid layer(s) along that line. 

To create a path profile from an existing line, select the line with the digitizer tool and then right-click in the main view of Global Mapper and choose Analysis/Measurement > Path Profile. 

 

​Do the images overlap?

When you have multiple image layers in Global Mapper that occupy some of the same area, they will overlap and the last drawn image will appear on top. You can change the draw order of layers in the Control Center by ​grabbing and dragging layers up and down the list. 

If you would like to blend the images together along the edges you may want to look into the Feathering options for the image layer appearing on top. Here you can feather out an edge of an image to help blend it into the underlying layer. 

 

​​Is there a way to show multiple surfaces in the 3D cutaway with the path profile tool?

​To view overlapping terrain layers in the 3D view you will need to ​enable the option to Draw Multiple Surfaces for Overlapping Terrain in Configuration > 3D View Properties. When you view a Path Profile cutaway in the 3D viewer multiple terrain surfaces will be displayed and cut away, but you will not see separate lines drawn on the cutaway face for the separate layers. 

​You can show multiple terrain layers the floating Path Profile window. To do this you will have to have multiple terrain layers loaded for an area, and you will have to enable a specific path profile setting. In the path profile settings, accessed from the Path Setup menu in the Path Profile view, check the option to Draw Separate Line for Path from Each Terrain Layer. 

 

​I​f you have two dates of elevation data would the two profiles show?

​You can show multiple terrain layers the floating Path Profile window if you have multiple to terrain layers loaded. To show multiple terrain layers in a Path Profile, enable the option to Draw Separate Line for Path from Each Terrain Layer in the path profile settings, accessed from the Path Setup menu in the Path Profile view.  

To view overlapping terrain layers in the 3D viewer you will need to enable the option to Draw Multiple Surfaces for Overlapping Terrain in Configuration > 3D View Properties

 

​​Has Global Mapper updated? I noticed you’re using v21.1​.

Version 21.1 of Global Mapper was released in February of 2020. ​You can download the new version of Global Mapper from the downloads page on our website. If your order is in current Maintenance and Support you are entitled to free version upgrades and should be able to license Global Mapper. If you are unsure about your Maintenance and Support status please contact our sales team, orders@bluemarblegeo.com, ​for further order assistance.

 

​​Does GM have the option to sunshade with a time/ date sun elevation for the location?

Currently, Global Mapper does not have an option to set the dynamic hill shade based on a date and time value. There is an open ticket on this issue, #GM-10988, that our development team is reviewing. 

 

​Using the dynamic hill shading is there a way to use the time of day to generate hill-shading?

Currently, Global Mapper does not have an option to set the dynamic hill shade based on a date and time value. There is an open ticket on this issue, #GM-10988, that our development team is reviewing. 

​Is there a modeling webinar using Global Mapper that you have available? 

We have recorded webinars available on our YouTube channel, BlueMarbleWebinars. What type of modeling information are you looking for? Here you can find a video on creating elevation grid layers from a 3D point cloud. 

 

Is there a way to take an average of those profiles?

In the Path Profile view, there is no way to create an average of the profile lines shown, but you can average the source elevation layers you have loaded. Using the Combine/Compare Terrain Layers tool in Global Mapper you can average the elevation values of loaded layers and generate a new layer. Then, when viewing your path profile this new average terrain layer should be drawn in the Path Profile. 

To show multiple terrain layers in a Path Profile, enable the option to Draw Separate Line for Path from Each Terrain Layer in the path profile settings, accessed from the Path Setup menu in the Path Profile view.

While you cannot take the average across all of the perpendicular path profiles, you can set an elevation corridor distance and display the average elevation along that corridor. In the Path Profile Settings under the Elevation Corridor section, set the type to Keep Average Elevation Along Perpendicular, and the Distance from Path to your desired perpendicular distance. This will show average elevation along the path filled in the path profile window, and a second line showing the elevation along the drawn path. 

 

Will Global Mapper work with underwater 3D models such as coral reefs?

G​lobal Mapper should display any loaded elevation layers or models, this includes layers describing underwater areas and reefs. 

 

​​So this tool creates the boundary of the lake without any input from the user?

The Create Areas from Equal Values tool takes input color values (RGB format) and generates area features by matching the color values in the image. In the lake example shown the lake was a distinct color from the surrounding ground area, so the tool was able to generate a feature bounding the lake based on the colors values in the image. 

 

Is the RBG value a number from 1 to 10 or so? 

RGB values are a color identifier commonly used to specify color values for pixels in images. An RGB value is three numbers representing the amount of Red, Green, and Blue in a specific color. The red, green, and blue values are on a scale from 0 to 255. 

 

How can you export in DWG all these profiles? Will it be one file with many profiles?

From the File menu of the Path Profile window you can select to Save Profile Line(s) to New Layer. When you select this option you can choose to then save All Cross Profiles. This will add 3D lines of the profiles to the main view of Global Mapper, you can then export this layer of features to any supported vector format. 

 

Can the axes in the 3D viewer be labeled with elevation, for the single terrain cutaway?

​Currently, in Global Mapper you cannot display the elevation values in 3D view, but the horizontal elevation guidelines are retained in the cutaway profile view. 

 

How do I alter the shader?

You can change the shader used for your elevation data with the Shader Drop-Down in the View toolbar. If you would like to alter the colors in a shader or create a completely new elevation shader, you can do so in Configuration > Shader Options

 

​​What happens if you choose a profile sampling distance smaller than the data resolution?

Since the source elevation data is a grid that is resampled to smooth between pixels, setting the path profile sampling distance to a value smaller than the source layer spacing will still result in a sampled path profile as you would expect. 

 

Can someone with the free version of acrobat still do some of the same interactions with pdf? 

Yes, you should still be able to view the PDF, toggle different layers on and off, and measure distances in Adobe Acrobat Reader. The layout is a bit different but you can find tools, like measure, on the Tools tab of the window. 

 

I am sorry if this is answered already, I’m having internet issues. Will this be available via recording?

Yes, all registered attendees to this webinar should receive an email in the next week or so with access to the recorded version of this webinar session. You can also register here to view recordings of past GeoTalks Express sessions. 

 

Can you feather grids like elevation data?

Yes, in the elevation layer options you will see the Feathering tab where you can set feathering options for your layer(s).

 

Can the 3D extruded features be color coded as well?

​Yes, the color styling options set in the Vector Options should be retained when you extrude the features using a selected attribute value. This allows you to create a both 3D by height, and 2D by color thematic map with your data. 

 

Does this 3D profile only work if you create the DEM in Global mapper? Can the elevation grid come from another software and saved that was saved as a .tif?

The Path Profile tool and the 3D path profile cutaway will work with any 3D elevation grid you have loaded into Global Mapper. This ogrid could be one created in the program or a grid loaded from a file, like an elevation TIFF. 

 

Can you then add lat and long to your job sites?

With the Find Address tool you can search for multiple addresses to find the positions (coordinates) for features or job sites. As demonstrated you can then create point features at those locations. 

 

Does this work with the perpendicular view you mentioned earlier?

​With a perpendicular path profile the 3D cutaway will not work directly from the path profile as you now have multiple path profile lines drawn. 

You can save the profile lines to a new layer from the File menu in the Path Profile window and then create new profiles from the saved lines one at a time viewing them in the 3D viewer with the cutaway option enabled. 

 

Can you automatically generate (or export) a series of profiles or profile data based on the streamflow lines generated in the Watershed tool? Or similarly a series of line features of any sort?

To create a Path Profile from an existing vector feature, select the feature with the digitizer, right-click in the main view and choose Analysis/Measurement > Path Profile. ​ Each profile will open in a separate tab of the Path Profile window and this option is limited to six-line features at a time. You can save or export a profile from the File menu in the Path Profile window. ​

 

​​Does the person opening the PDF need Adobe Acrobat Pro to turn on and off layers?

​No, you should still be able to view the PDF, toggle different layers on and off, and measure distances in the free Adobe Acrobat Reader. The layout is a bit different but you can find tools, like measure, on the tools tab of the window and the layers sidebar on the left of the main PDF view. 

 

Any way to save viewpoints in 3D view?

You can save an image of your data displayed in the 3D viewer by using the Save Image button (camera icon) in the 3D view window. This will capture the current view and save it to an image file format. 

 

Does the smooth function just smooth once from the original roughness or does the effect stack?

You can smooth features multiple times and the effects will stack on top of each other making the lines appear smoother each time you apply the tool.  

 

Can you feather along a partial length of an edge?

When specifying an edge of an image to feather along, you can only select the whole edge with the checkboxes available on the Feathering options tab of the Layer Options. 

That being said, there are some additional options in the feathering dialog to feather the data with respect to a selected polygon. Depending on what you are trying to achieve this option to use a polygon feature for the feathering bounds may work for you, although the data will be feathered along all sides of the selected polygon(s). 

 

Does the pdf contain the coordinate system for the geospatial tool? Does it do eastings and nothings too based on the projection in GM?

While the Geospatial PDF file will retain the workspace projection, as set in Configuration > Projection, if loaded back into Global Mapper or a GIS program, the coordinates displayed in Adobe will be shown in geographic latitude/longitude values. 

 

Are the profile axes visible in the 3D window?

Currently, in Global Mapper you cannot display the axis values in the 3D view for a path profile cutaway. However, the horizontal elevation guidelines are retained in the cutaway profile view to provide some reference.   

 

Can we use that tool with the coast line?

You can draw a path profile along the coastline and display it. You can also generate a path profile from an existing vector feature if you already have a line representing the coastline. Both of these methods allow you to enable the perpendicular path profiles option, which you can do in the path profile settings, before or after creating a path profile. 

 

Is it possible for the perpendicular path profiles to have varying widths, such as being constrained to a hydrographic feature polygon?

After creating the path profiles, you can use the Path Profile File menu option to save the profile lines to a layer in the Global Mapper workspace. This will save a layer with a 3D line for each profile. You can then crop these line features to a specific area like a hydrological feature.

 

​When demonstrating the Voronoi/Thiessen diagram with rainfall collection data, you suggested we use watershed/catch basins instead of doing the Voronoi/Thiessen analysis. While this is a great suggestion for an analysis and thematic mapping, it requires a different workflow. 

For your suggested workflow you would need not only the rainfall measure points, but also the watershed area features. You can generate watershed areas with an elevation grid and the Watershed Creation tool in Global Mapper. With the rainfall point data, and the watershed areas, you can copy attributes from nearby/overlapping features to apply the rainfall amounts from the point features to the watershed features. This would then allow you to generate a thematic map of the watershed areas based on the measured rainfall data.

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