3DM Viewer Quick Start Guide¶

3DM Viewer is a free viewer that can display 3DM Analyst projects and may be redistributed to others for that purpose. It also includes the ability to make basic distance measurements and check the orientations of planar features.

It can also be used to check compatibility of 3DM Analyst with various file formats.

(Contact ADAM Technology if you do not currently have 3DM Viewer and you would like to use it.)

Loading Data¶

Opening a 3DM Analyst Project¶

A .vwr file is 3DM Analyst’s native project file format. It is used to tie together one or more DTMs, digitised or generated vector, point, or planar data, and various project settings.

A .vwr project can be opened from the initial Images View using the Open toolbar button () or from any view using the File | Open Project menu (Ctrl + O). All assets associated with the .vwr project will be loaded:

A green check mark indicates that the asset was found and loaded successfully; a cyan dash indicates that the asset was not included in the project; and a red cross indicates that the asset was included in the project but could not be found.

Even without a .vwr file, 3DM Viewer can manually load in all of the various assets that would normally be referenced by a .vwr file.

Opening a DTM¶

DTMs can be loaded in the following file formats:

Supported DTM File Formats¶
Format	File extension	Includes surface model	Includes texture
Native DTM	`.dtm`, `.dtmx`	✓	✓
ADAM RAW	`.raw`	✓	✓
DXF v12–v2004	`.dxf`	✓	✗
Vulcan	`.00t`	✓	✓
Wavefront	`.obj`	✓	✓
ASCII	`.xyz`, `.pts`	✗	✗

(The difference between the two ASCII file formats is that .pts files can have optional RGB colour information per point while .xyz files can have optional intensity information per point. You can simply rename the file extension prior to import if required.)

All can be loaded using the Load Extended DTMs toolbar button in the 3D View or from any view using the menus File | DTM | Load Extended (which has the same effect as the toolbar button) or File | DTM | Load (which is only possible if a .vwr project has been loaded that includes stereo epipolar images and was not simply a container for a set of DTMs).

The key difference between Load Extended and Load is apparent when loading one of the ASCII point file formats. In the former case, since there is no orientation or image information associated with the point cloud, 3DM Viewer will automatically triangulate the points with a 2.5D surface reconstruction using the Z axis. If a stereo model was loaded and the Load menu was used, 3DM Viewer will instead triangulate the points using the left image and drape it over the surface afterwards.

For other DTMs types it will generally be better to load them using Load Extended because that will import the DTM as-is, whereas Load will also project it into the current model and trim any parts that lie beyond the model boundary.

Opening a Point Cloud¶

3DM Viewer supports the following file formats for point clouds:

Supported Point Cloud File Formats¶
Format	File extension	Includes colour/intensity	Includes normals
Native Point Cloud	`.ptc`	✓	✓
ASCII	`.xyz`, `.pts`	✓	✗
LAS	`.las`, `.laz`	✓	✗

(As above, the difference ASCII point formats is that .pts files can have optional RGB colour information per point while .xyz files can have optional intensity information per point.)

Since 3DM Viewer can only view data, the primary purposes of loading a point cloud would be to (a) check format compatibility with 3DM Analyst, and (b) check other data against an existing point cloud for verification. (3DM Analyst can also generate a DTM from a loaded point cloud.)

Loading Digitised and Generated Data¶

3DM Viewer supports 3DM Analyst native .pln file format for loading digitised data, as well as certain types of automatically generated data (e.g. contours, cross-sections, etc.).

To load a .pln file, use the menu File | Features | Load.

DEMs are stored in a separate .dem file. These are 3DM Analyst’s native file format for a height-only regular gridded DEM and they are loaded using the menu File | DEM | Load.

Viewing Data¶

Display Options¶

Click on the tab at the bottom of the window to access the 3D View.

The first group of items in the 3D View toolbar control the display of various items:

Buttons	Item Shown/Hidden
	XYZ co-ordinate axes/Scalebar/Compass (see this post for details)
	Control points, if there are any
	Control point IDs, if there are any
	Derived relative-only point locations, after a bundle adjustment
	Camera locations (only after a bundle adjustment if they were not surveyed beforehand)

If a DTM has been loaded, the next group of buttons on the toolbar control the display of the DTM(s):

Button	DTM Rendering Option
	Point Cloud mode
	Wireframe mode/Textured wireframe mode (see this post for details)
	Solid Surface mode
	In Point Cloud mode, renders a colourised point cloud; in Solid Surface mode, applies the texture to the surface

Use your mouse to zoom, rotate and pan around your 3D view:

Hold the left mouse button and drag to rotate the scene about the current vertical and horizontal axes respectively. (The centre of rotation is actually a 3D point in the scene that is in the centre of the view. Later we will see how to centre the view on an arbitrary point in the scene to make it easier to control what the scene is rotating about.)
Hold the right mouse button and drag to pan. This can also be used to adjust the centre of rotation.
Hold both mouse buttons and drag vertically to zoom. (You can also use the scroll wheel to zoom.)
Hold both mouse buttons and drag horizontally to rotate the current view about the view axis (i.e. a barrel roll).
Use the Recentre button () to re-centre the current view. It puts the midpoint of the enclosing box of all currently displayed items (including camera points and axes arrows, if they are displayed) at the screen centre and sets it as the rotation point. It sets the scale so everything appears on the screen, views from the top (that is, the -Z direction) and puts the Y axis (which is usually North) to the top of the screen.
Use the axis view direction buttons in the Tool Bar to jump to views that are aligned with the coordinate system axes:

Button	Direction	Normal meaning in a real-world co-ordinate system
	`-Z`	View from above, looking down
	`+Z`	View from below, looking up
	`+X`	View from the west, looking east
	`-X`	View from the east, looking west
	`+Y`	View from the south, looking north
	`-Y`	View from the north, looking south

Making Measurements¶

Before you can make measurements in the 3D View, it’s important to note that there are up to two cursors visible on the screen:

Mouse cursor

The mouse cursor, which is controlled by the mouse and moves in 2D in screen coordinates in the usual way.

3D Cursor

A separate cursor, which is represented by a small, yellow “3D Axes” shape that interacts with your DTM and can be hidden behind it. This cursor has a 3D position in your ground coordinate space and the “3D Axes” shape is oriented along this coordinate system with X represented by red, Y by green and Z by blue. (This cursor is usually off-screen when the 3D View is first displayed.)

As this cursor moves around the model, its ground coordinates are shown in the status bar at the bottom of the screen, together with the dip and dip direction of the DTM at the location of the cursor.

The 3D Cursor is normally controlled by the mouse by entering “Terrain Following Mode”. In this mode, the 3D Cursor can be made to follow the location of the mouse cursor, positioned on the DTM in 3D at the place where the mouse cursor lies over the DTM.

This mode can be turned on and off in two ways:

Ctrl:: When you press and hold Ctrl, the 3D Cursor will follow the movement of the mouse over the DTM. When you release the Ctrl key, the 3D Cursor will stay in its present position.
Tab:: Tab will toggle the 3D Cursor’s following mode. Ctrl has no effect if cursor following mode has been activated with Tab.

If you move the mouse off the DTM, the 3D Cursor will stop at the DTM edge.

Tip

It is usually easiest and fastest to use your little finger on Ctrl rather than use the Tab , because you can easily lift your finger when you want to do some other mouse operation, such as clicking on a Tool Bar button. You may need to practise this a little!

The other way to control the 3D Cursor using the mouse is to turn off Terrain Following Mode and then toggle the the Lock Orientation button () or press L. Then you can move the 3D cursor with the right mouse button and it will move in the plane parallel to the screen plane, independent of the DTM and not limited to the extents of the DTM. You can position the 3D Cursor at any location in 3D by using this mode twice with two different orientations. Turn this mode off by pressing L or clicking the Lock Orientation button () again.

You can also use the 3D Cursor to control the 3D View: Use the Recentre 3D Cursor button () or press Home to set the current 3D Cursor position into the centre of the screen and also make it the centre of rotation of the view.

Distance measurement¶

Distance measurement works differently depending on whether a planar feature has been “snapped” or not. (A feature is “snapped” by moving the 3D Cursor close to it and then pressing Enter. It can be “unsnapped” simply by pressing Esc.)

For a normal distance measurement between any two points, position the 3D Cursor over the first point and then press D. Then move the 3D Cursor to the second point; as the 3D Cursor moves, the distance to the first point is shown at the bottom-right of the window and a line depicting the distance being measured is shown onscreen.

For a distance-to-plane measurement, first snap on to a plane feature (a purple outline will indicate which feature has been snapped) and then press D. Now, as the 3D Cursor moves, the distance to the nearest point on the snapped plane will be shown instead. If the nearest point is within the extents of the plane then the line connecting the 3D Cursor to the plane will be rendered in cyan; if it is not, it will be rendered in red.

Angle measurement¶

To measure the relative angle between two planes, perform a distance-to-plane measurement as above, but move the 3D Cursor to a second plane and then press Enter to snap on to the second plane; the Dist. to Plane report at the bottom of the window will update to also show Rel. Angle in degrees. Note that this is the true 3D angle between the two planes, not the difference in dip and dip direction separately.

Viewing Feature Information¶

When any feature is snapped, press I to bring up the Feature Info dialog for that feature. For plane features, the dialog will show the feature’s location, it’s dip and dip direction, it’s max. chord length (maximum distance between any two points digitised when capturing the feature) and size (by default the same as the max. chord length but can be over-ridden by the user after capturing), and various annotations and any user-defined fields that the user might have added, plus spacing information if it was recorded or generated: