Introduction to Application Layers¶
This chapter provides an introduction to application layers in Gemini Terrain. Here you will learn about the different types of application layers, how they are organized, their properties, and how to work efficiently with them in the program.
Types of Application Layers¶
In Gemini Terrain, you can work with several different types of application layers (app layers). These are distinguished by different symbols in the user interface, and you typically give them names that describe their content.
App Layers
Application layers are often abbreviated to "app layers" in Gemini Terrain and represent one of the program's most important concepts for organizing and structuring geodata.
App layers can be of the following types:
- Standard (gmi file, file type TER)
- Surveying (gmi file with observations, file type SURVEY)
- Raster
- BGR-tiled
- WMS client
- WMTS client
- WFS client
- WCS client
Standard Application Layers¶
Standard application layers are Gemini Terrain's internal vector format. This is a general storage structure for geometry and attributes that allows you to store many types of geographic data, typically:
- Map data
- Plan data
- Surveyed data
These app layers are central to Gemini Terrain and are described in detail in the subsequent chapters.
Surveying App Layers
Surveying app layers have specific functions and are described in a separate main chapter.
Raster Application Layers¶
To handle raster data, we have two types:
- Raster - Points to an image file with no limitation on image size
- BGR-tiled - Supports multiple map sources in raster form
BGR-tiled limitation
BGR-tiled app layers have a limitation on image sizes (2 GB).
The BGR-tiled layer points to a bgr file (control file) that contains:
- Path and filename for the raster files
- Extent (lower left and upper right corner) of the raster files
You can combine different formats (e.g., TIF and JPG) in the same control file. To add one or more raster maps to a control file, you need a georeference file (e.g., mmm-, sos-, or tfw-file) that describes the geographic location of the image. The program assumes that this file is located in the same directory and has the same base name as the raster file.
Web-based Application Layers¶
The Norwegian Mapping Authority (Kartverket) offers several free WMS viewing services that can be used freely according to the current terms of use.
Web Map Service (WMS) is one of the Open Geospatial Consortium (OGC) standards for producing scalable maps that can be displayed on a screen. The maps:
- Are geographically referenced in one or more internationally accepted coordinate systems
- Are presented as digital image files (e.g., PNG, GIF, or JPEG)
The Application Layer List¶
The program has a dedicated vertical list window for application layers.
Empty list window for app layers
The list window can have four columns:
- Show - To turn the layer display on/off
- Application Layer (abbreviated App Layer) - Shows the layer name
- Type - Shows the layer type
- Drawing Layer - Shows connection to drawing layer
Customize Column View
Right-clicking on the column header brings up a menu where you can select which columns to display in the list.
The application layer window provides access to several functions for controlling how layers are displayed and behave. Here are the most important functions:
Set Active (A)¶
When you set an app layer active, its content will be displayed in the horizontal list window. New objects are created in the active layer, unless the function has its own choice for the result app layer. When you need to edit an object in an app layer, the app layer holding the object must be active.
Show (V)¶
With this option, you can turn the layer display on/off. The function is available both by left-clicking on the eye icon, or by right-clicking on the app layer and activating/deactivating Show (V).
Shortcut key [V]
Use the shortcut key [V] to quickly turn display on/off. You can also use this shortcut key for multiple layers simultaneously by selecting multiple layers first.
Open for Editing (E)¶
You can run the program in single-user or multi-user mode. Single-user mode is the default setting for new local projects, while multi-user mode is the only option for cloud projects.
In multi-user mode, the application layers and models will be locked for editing. The user must manually open the layers that need to be edited for editing.
Draw on Top (T)¶
The drawing order in Gemini Terrain normally follows this logic:
- First, application layers are drawn from the bottom of the list and upward
- Then, inserted models are drawn, such as roads, excavations, DWGs, and IFCs
Practical Use
When a road uses model presentation with area filling, it can be difficult to see objects from application layers that lie above or below the road physically, because roads are drawn last. With Draw on Top you can force the drawing of one or more application layers on top.
Shortcut key [T]
Use the shortcut key [T] to quickly turn this function on/off. You can also use this shortcut key for multiple layers simultaneously.
Passive in Drawing (P)¶
When setting an application layer as passive:
- The geometry is drawn as usual
- The data is not clickable or editable
- The drawing of data can be faster
Passive application layers are indicated with a "P" before the name.
Shortcut key [P]
Use the shortcut key [P] to quickly turn this function on/off.
Low Detail Level in Drawing (L)¶
When an app layer is set to be drawn with a low detail level, figures, hatching, dashed lines and so on are not drawn. This can increase performance in some cases. Application layers with low detail level are indicated with a "L" before the name.
Shortcut key [L]
Use the shortcut key [L] to quickly turn this function on/off.
Show Terrain Grid (G)¶
With this option, you can quickly turn the terrain grid on/off for app layers that have a defined stratum.
Shortcut key [G]
Use the shortcut key [G] to quickly turn the terrain grid display on/off.
Working with Application Layers¶
Application Layer Statuses¶
Application layers can have different statuses that are visually displayed in the application layer list:
- Bold black text - Indicates that the layer is active. The content is displayed in the horizontal list field, and new objects are created on this layer.
- Gray text - Indicates that the display is turned off, the data is not drawn on the screen.
Interaction with Application Layers¶
You can interact with the application layers in several ways:
- Left-click on the layer name to select the layer (the entire row turns blue)
- Right-click on a selected layer to bring up the context menu with available functions
- Drag and drop to change the order of the layers. Alternatively with the keys [U] (Up) and [D] (Down).
Organization in Groups¶
You can organize application layers in groups to maintain order in the drawing.
The example shows FKB data grouped in the group FKB-data**
We can also group app layers that naturally belong together. Empty groups are also allowed, for example for use in project templates. Multiple group levels are also possible.
Effective Organization
A good group structure makes it easier to navigate in projects with many application layers. Consider creating groups based on data sources, professional fields, or project phases.
Application Layers that Fail to Load¶
In some cases, application layers may disappear from the drawings, especially in cloud projects. This happens if the app layers cannot be loaded during opening and are therefore omitted from the application layer list.
Example: The app layer Innmålte-data has failed to load
App layers that fail are handled as follows:
- Remain in the list but get an "invalid" status
- Are marked with a special icon (red X) indicating this problem
- Are treated as non-editable (editing menus are automatically grayed out)
There can be several reasons why it fails to load, for example that it has been deleted in Gemini Connected web.
If the file can be loaded again, for example because it has been restored, the status will change back to valid.
Symbols and Types¶
Different symbols are displayed in front of the app layer name depending on the type of app layer. For example:
- WMS layers have their own symbols
- BGR layers have their own symbols
- Gmi layers defined as strata have their own symbols for the stratum type
Strata
Left-clicking in the Strata column will open the dialog for setting strata. In the chapter Defining Strata, we cover strata, which involves defining a gmi layer as a stratum (layer in the ground).
Connection to Drawing Layers¶
All application layers have a connection to drawing layers (DDS-CAD), which can be displayed in the application layer list. You can make this connection visible by right-clicking on the column header and checking Drawing Layer.
With drawing layers, we can turn application layers on/off in an alternative way with the Show Layers function on the toolbar, and can get several advantages:
Advantages of drawing layers:
- Faster on/off functionality - When using drawing layers, there is no screen refresh (all data remains in memory), which makes on/off operations much faster
- Grouping of application layers - You can connect many application layers to the same drawing layer (e.g., all zoning plan layers) and thus turn many application layers on/off with one keystroke
- Presentation-specific display - The light bulb in drawing layers only applies to the active presentation, so the layer can be on in plan view and off in 3D view
DDS-CAD Platform
In the section on the DDS-CAD platform, the layer handling for the command file for drawings is described in more detail.
Practical Examples¶
For practical implementation of working with application layers, see the following examples: