The Digitise tab contains a lot of the functionality necessary to manually extract 3d Point and Line data from a point cloud. In essence, once the process is started (by clicking Select Points), coded data can be picked up with the click of a mouse very quickly and easily. Much faster than someone could walk a site to pick up the same detail (assuming the point cloud has all the pertinent data).
During the digitising process, comma codes can be added to the points just as if the data was being collected with a total station or GNSS. They can also be triggered with the appropriate key whilst the digitise tool is active.
If a Tangent comma code is used, whilst there is no current curving, then Curving will automatically be enabled after the Tangent point has been recorded. If Curving is active, however, then curving will be deactivated after an end Tangent is used. Similarly, if a Discontinuity is used, the curving will be reactivated afterwards.
The Codes of the points generated during the digitising process is obviously critical to getting the desired output. Codes should be selected in exactly the same way they would be during an actual survey.
The current code to be used can be selected from the Code dropdown box. String numbers can be appended to them simply by typing one in after the code. During the digitising process, codes can be added to a pallet simply by pressing Add Code. Conversely, they can be removed via Remove Code. The code pallets are accessible in the 3d view as shown below, and also in a section view. To change code simply click on the required code, or press Space Bar to cycle through them.
The Tools section controls the digitising process and allows various height modes to be used. The controls are as follows.
- Select Points: This button actually Starts and Stops digitising. Note digitising can also be cancelled with a right click of the mouse. Also, if a section view is active, then the digitised points can only be digitised in the section view. The 3d view will not allow digitising of points until the section window is either hidden or closed.
- Show Distance: Attaches a running distance to the screen as points are digitised. Helps to insert points at regular distances as if they were being placed on site.
- Pick Fixed Height: Allows the height of an indicated point to be remembered and subsequently applied to any newly picked points (if the Height Mode is set to Fixed Height).
- Height Mode:
- No Offset - No additional offset is applied to the height of a digitised point.
- Vertical Offset - The height of a digitised point will be offset by the value in the Height box.
- Fixed Height - Applies the height of a previously indicated point to the newly clicked points. Use the Pick Fixed Height button to set the point to be used.
- Normal Offset - Offsets a point in the direction of the normal i.e. perpendicular to an indicated DTM triangle. The actual distance being defined by the Height box.
- Free Select: If this option is enabled, then a point can be digitised anywhere within the confines of a section view. Therefore if a piece of detail is missing, the location of where a corner may be for instance, can still be clicked.
- Plane Projection: When enabled this snaps the digitised points to the plane of the current section. This option is auto-enabled when the Free Select is used.
The least squares circle finder is a handy tool to help determine the centres and diameters/radius of trees, lampposts or pipework etc... This tool normally works hand in hand with the quick horizontal/vertical section options. As those sections create small localized sections that touch the surface of the object in question. Any close surrounding data that may get in the way, is therefore kept to a minimum. The various options are as follows.
- Find Circle: Assuming a suitable section is ready, this will try and find the best fit circle from the points contained within the section view.
- Define Polygon: Sometimes it may be impossible to get a section that is devoid of noise or just contains data that is so close to the object it will always get in the way. For these situations the define polygon option allows a portion of the section view to be highlighted so that only points in that area are used for the calculation. having indicated the relevant area press Enter to set it.
- Digitise Circle: Use the current centre point and diameter/radius values to digitise a point using the current code.
- Set Center: Moves the centre of the current section to a new location, so another object can be digitised.
- Auto Find: With this enabled n4ce will constantly recalculate the best fit circle as the section plane is moved up and down or otherwise repositioned.
- Keep Circle: Locks the current circle in place. Thereby allowing the section to be slid down to ground level say to record the actual position of the detail point. Rather than it being held up in the air.
- Decimal Places: Defines the number of decimal places to use when storing (as an attribute) the Diameter or Radius (Code depending) of the current object.
When points are being added to the model, the Digitise Points tool properties provides quick access to options that help control what is locked to and also exposes attributes that can be populated during the survey process.
- Height Mode: Discussed Above.
- Pick Fixed Height: Picks the height to be used when the level of digitised points is to be fixed.
- Pick Mode: Defines whether scan points nearest, or furthest from the camera are picked.
- Lock Mode: Controls the type of data the digitise tool should lock too. I.e. Between the point cloud or surveyed features.
- String Lock Mode: When locking to features, this enables users to lock to the End, Mid or Nearest points to where the cursor has been clicked.
- Pick Precision: This pick precision improves the picking of data closer to the camera so that the points behind are not accidentally picked instead. Course can be thought of as picking with a finger. Whereas Fine is pin sharp.
- Intellisphere Mode: Enables spherical picking based on a given radius. This allows the closest, furthest, average, lowest or highest point within the sphere to be selected.
- Attributes: This allows user-definable attributes, as well as predefined ones to be entered for a given survey point. By default P & W are added so that Parallel and Width attributes can be entered without them needing to be predefined on the code. The attributes that follow come from the Fields tab of the current code.
- Show Distance: Attaches a realtime measurement to the screen that shows the distance to the previous point. This allows a user to ensure detail is still collected at a close enough spacing as if pacing on-site between points.
- Post Code: Allows the attributes to be set after the point is clicked on screen. The attributes can be changed until the next point is picked, or the digitising is cancelled.
- 2 Point Height: Allows the height of the selected points to be set with a second click. So the first defines its plan position, the height is then set with the second selection. This is useful for example when picking points on a kerb bottom, but the detail is missing or full of debris. This can also be accomplished via the \ key as the first point is located. A height will then be shown on screen to depict that of the second location before it is confirmed.