GeoTalks Express – Session 1 Questions & Answers

The first in Blue Marble’s GeoTalks Express online webinar series, entitled Getting to Know Global Mapper, was conducted on April 1st 2020. During the live session, there were a number of questions submitted to the presenters. The following is a list of these questions and the answers provided by Blue Marble’s technical support team.


What is the spatial extent of the data being loaded? 

I believe that you were asking this question in reference to loading data from an online source. When loading online data you have a few options to choose the extent to load. The extent is specified in the connect to online data dialog and you can load data for only the current screen bounds, within a certain distance of an address or coordinate, within a selected area feature, or for the entire source bounds. In the session today I demonstrated loading only data for the current screen bounds. 

When loading data from an online source keep in mind that this data is streamed and relies on your network connection to load the data. Smaller areas of data will likely load faster.


How do you define the bin sizes in the depth example?

When setting up the point styles for the lake depth points I manually entered and set the style for each value using the New Value button on the Point Styles tab. 

You can use the Load Values option to automatically load values from a layer of features. You can load each unique value, or if the values are numeric Global Mapper will recognize this and give you the option to load only key values (minimum, average, average + two standard deviations, maximum) and then blend the colors between these values. 


How do you get contour lines? 

In Global Mapper contour lines are created from a loaded elevation grid layer using the generate contours tool. In this tool there are many options for generating contour lines including the option to set a specific contour interval in meters or feet. 


Is it possible to know the date from World Image Data?

Blue Marble does not create or update any of the data streamed from the online sources. For more information on any built-in online source, image or otherwise, you can right-click on the source name from the Online Sources dialog and select to Display Source Web Page/Terms of Service


Can Global Mapper produce contours from point data?

Contour lines need to be created from an elevation grid layer. You can generate an elevation grid from 3D point data, and from there generate contour lines


Can the fly through be saved as a file? 

Yes, you can save a fly through as a video. From the 3D viewer click on the save the fly through button on the toolbar and you will have options to select the quality, resolution, frame rate, and format for the video recording of the fly through. 


If you delete something is there an undo button?

You can use the keyboard shortcut ctrl + z to undo deleting features right after you have deleted them. This undo function only covers the last feature(s) you deleted and will not work if you delete a feature and then perform another action in Global Mapper. 


Is the profile view 1:1 or is it vertically exaggerated? 

The path profile view is exaggerated to fill the path profile window. There are values noted on both the x and y axes of the profile view. You can specify a specific elevation range or scale for this tool in the Path Profile Settings


Can you talk about how to find free lidar data online?

There is freely available lidar data out there. In Global Mapper we include some of these sources in the Online Sources dialog. There is a LIDAR folder you can expand and the sources listed here will link you to an organization’s download page where you can then download data for your area of interest. 


Do the menu tiles – icons highlight only when applicable choice? The pencil selects as edit – the feature chosen triggers other option choices?

Specific to the digitizer toolbars, you may have noticed that some tool icons appear grayed out and are unable to be selected. This is true for many feature editing tools until you select a feature with the digitizer. Once you have a feature selected you should see these options brighten and be selectable based on the feature(s) you have selected. 


What do the tree and building toolbar buttons do?

These buttons are part of the Lidar Classification toolbars that are used to work with point cloud data in the Lidar Module. We will be talking about the Lidar Module in the next GeoTalks Express session on April 15th. 

We do have previously recorded webinars and videos that specifically focus on and talk about the Lidar Module if you are interested in learning more about this module now. You can find these videos here on our YouTube channel


How are the lat and long extents set up in the map layout editor?

When you create a map layout you select with the bounds or the scale and center point of the data that should be displayed in the map layout. To add coordinate grid elements to the map, click to select the map frame then right-click and select Properties. Here you can edit the map view element and on the Grid Fram tab add coordinate grid information to the map view. 


Can we georeference a scanned map in Global Mapper? 

Yes, you can georeference scanned maps and other layers in Global Mapper. To georeference a layer you would use the Rectification tool. For this tool you should start by loading some reference data into Global Mapper, then from the File menu select Rectify (geo reference) Imagery to load your scanned map image and open the Image Rectifier dialog. 


Is there any way to create contours with intervals less than 1m or 1ft?

Yes, you can specify a contour interval in the contour generation tool dialog. The only unit options are meters and feet, but you can use decimal values to specify a smaller contour interval. 


Can you export a path profile as a point or CSV file?

You can export a path profile to multiple formats from the File menu in the path profile dialog. From this menu you have options to export the profile as a CSV or XYZ file. 


Can Global Mapper incorporate multiple surface models so the profile view shows more than one profile? 

Yes, if you have multiple overlapping terrain layers loaded in Global Mapper you can create a path profile view that will show separate lines for all terrain layers. To enable this option you will need to go to the Path Profile Settings and check the option to Draw Separate Line for Path from Each Terrain Layer. In addition you can enable the option to Draw Legend when Drawing Separate Layer Lines


When importing USG 3DEP elevation data – is there a way to know its accuracy and time/date of collection?

Blue Marble does not create or update any of the data streamed from the online sources. For more information on any built-in online source, image or otherwise, you can right-click on the source name from the Online Sources dialog and select to Display Source Web Page/Terms of Service


Can you create a contour map from the lake points or a thematic map? Like a heat map?

From the lake depth points used as an example, you could generate an elevation grid to show depth, and generate contour lines from that gridded elevation layer. 

You can create a thematic map by changing the point style for the lake depth points in the layer options. 

Global Mapper also has a density or heat map tool that you can use to show clusters of points or attribute values. 


How can you extract an area to AutoCAD Civil 3D? Image? Terrain?

Global Mapper supports many file formats for both import and export. For vector features these do include common AutoCad formats DWG and DXF. For raster image and elevation formats Global Mapper has many options including JP2000 (image), GeoTIFF (image or elevation), and DEM (elevation). Are there specific formats you are looking to work with?


Can you do image registration in Global Mapper?

You can georeference images and other layers in Global Mapper. To georeference a layer you would use the Rectification tool. For this tool you should start by loading some reference data into Global Mapper, then from the File menu select Rectify (geo reference) Imagery to load your scanned map image and open the Image Rectifier dialog. If you are looking to adjust the rectification for a layer, right-click on the layer in the control center and select Rectify


Can you make final presentation plots with title box and other presentation features?

Yes, you can create maps with titles, legends, and other elements using the Map Layout Editor. From here you can export the pages to PDF files or images for use in presentations. 


Can you use this to show areas of a certain percent slope, like slopes greater than 20%?

In Global Mapper you can use a custom shader to show specific slope values or slopes over a certain threshold in a different color. When creating a custom shader the slope values should be specified as degrees. 

You also have the option to create vector features from slope values by using the Create Areas from Equal Values tool. You can then search these vector features to identify and work further with a specific slope value or range of values. 


Can the 3D-views generated by the fly-through tool all be exported in a batch?

If you have multiple fly-through paths defined in Global Mapper, when you go to save the fly-through you will be prompted to select a path in the Fly-Through Options dialog. You can select All Paths which will play and record all the fly throughs back to back recording them to one video file.


Are there any size limits on vector files?

Although there are no size limits on files when working in Global Mapper, you should make sure that your computer is powerful enough to handle the size of data you are working with and the processes you are running. We do have some system requirements and recommendations for running Global Mapper, but an issue some users run into is insufficient memory when performing analysis functions with large datasets. 


Is it possible to change the units in the path profile?

Yes, you can change the distance units in Global Mapper and the elevation units used in the Path Profile tool. To change the distance units (x axis units in the path profile) go to Configuration > General > Measure/Units and change the Distance Units. To change the elevation units in the path profile (y axis units) open the Path Profile Settings and change the Elevation Display Units.


What projection does the feature retain? Can we specify the coordinate system when exporting?

When exporting features or layers Global Mapper will use the workspace projection to write out the files. The workspace projection is also what is used to draw and display the data in Global Mapper. This projection can be viewed, set, and changed in Configuration > Projection


Can you round this calculation to a desired precision?

If you are asking about precision related to calculating new attributes, you can use a function to specify a number of decimal places for a numeric value. 

  • FIXED(expression1 [, expression2]) : Formats expression1 as a numeric value, to an optional number of decimal places, specified by expression2, if present; if it’s not present, then the default is 2 decimal places.


Do you have more style options for the scale bar?

In the Map Layout Editor you can edit the scale bar feature to customize aspects like font, spacing, and color. All added elements are able to be edited like this in the Map Layout Editor. 


If you crop and image, can you export only the cropped area and if so, what resolution will it keep? 

When you crop an image the image still displays with the original resolution. When exporting an image Global Mapper will export the image that is shown, so if an area is cropped out that area will not be exported. In the export options you do have the option to specify the resolution for the exported image. 


I’m a secondary science teacher (grades 7-12) that teaches earth science. Do you think the global mapper can be applied to teaching topographic mapping? It seems a bit too difficult for students (who are around 14-15 years old) to use, but maybe there’s something that I could do with it as a demonstration tool.

In Global Mapper you can most certainly work with and create topographic maps. Take a look at the generate contours tool to show and have students understand how contour lines fit a gridded elevation surface. With the 3D viewer and path profile tool you could show how the 3D data/information is translated to a flat or 2D map. 

If you are unfamiliar with Global Mapper I encourage you to request a trial license and start by looking at the Getting Started Guide, and maybe some of our self training lessons


How do we change the openspace label zoom during exporting raster images?

When viewing online data, like the World Street Maps or Open Street Maps data, that has labeled areas and features, these labels are part of the raster image. This means that the scale of the features and labels is linked to the zoom level of the online source.

You can control some of the detail shown for online layers on the Display tab of the layer options. In this dialog you should see a slider for Online Layer Detail Offset that can be used to adjust the amount of detail shown based on using a higher or lower zoom level for the online data. 


How can I generate a database of points over the image?

If you are looking to generate a regular grid of point features over a loaded image layer, you can use the Create Regular Grid of Features tool from the digitizer (advanced) toolbar. This tool will generate a grid of features (points, lines, or areas) and you can select under Grid Placement/Orientation to fill rectangle. Using the Select Rectangle button you can then set the bounds to the bounds of a specific image layer.


Can I draw a line joining the deepest or shallowest depth points of a dataset?

With the digitizer tools in Global Mapper you can select specific points and then choose to create lines features from selected points. To select points to connect into lines, you can search the vector data for features based on an attribute value and select them, or select features more directly with the digitizer tool. 

Additionally, you can generate a gridded elevation layer for the depth points and then perform further analysis. Some analysis functions Global Mapper supports are the generation of contour lines and watershed and stream creation over an area of known elevation. 

I see that you were interested in creating or working with a bathymetric surface with water shading

If you do not have a bathymetric surface, but instead have point features like in the Lake Depth example shown during the GeoTalks Express session, you can generate a gridded layer from this 3D vector data. You can then shade this layer with any of the built in shaders, or create a custom shader to show the colors/values you would like. 

You also have an option to display a water level at a specific elevation which would allow you to show a water line along a coastal area or bank. 

Leave a Reply

Your email address will not be published. Required fields are marked *