CAD is an integral part of n4ce. In its simplest form, it can be used as an electronic drawing board allowing you to create your own detailed drawings.
Note the distinction between Models and CAD. Models use the Code Table to create graphical elements whilst CAD uses drawn elements, with no relationship to your survey codes. Models are “clever” with ripple through updtaes!
Symbols used in your surveys are created in CAD, either directly in n4ce or imported into CAD from external files, such as DWG, DXF, OS MastermapTM or DOT. The latter is used to transfer data between n4ce and earlier AiC packages like ProSURVEYOR and DOS 4CE.
CAD is at the heart of Drawings, which are used to create final presentations of your surveys using View Ports with Paper Space and Model Space. Standard Templates can be created containing your tables and notes.
Models have their own Dedicated CAD Backcloth used by n4ce to draw Tables, Contours, Hatching and Committed elements from your survey. Access to this special backcloth is provided using the Pencil Icons.
A useful feature is the ability to Extract coordinate data from CAD drawings for setting out. This is made possible by using either normal or dedicated backcloths and will be demonstrated in the following exercise.
Normal backcloths provide the facility to overlay CAD, Model, alignments and/or Images onto another graphics view.
If the Lock options are active, then vector detail in these Backcloths will become accessible. This only applies to vector and not raster images.
Exercise 7. Using CAD and Backcloths
Backcloths can be plotted and exported as part of the current display, but greater control can be exercised using Drawings (see later).
Note Don’t save this or other existing Exercises, unless you intend to, otherwise training data may become modified and unusable by others
- Create a New Project. If you are leaving an exercise you will be invited to Save the current Project. Try using Save As to save the Project with a new name.
Note This new Project will be called Untitled, by default.
- Right click over the CAD folder in the Project Tree and select Import. If necessary, navigate to the ..\Training folder. Set File of Type to DXF then select the file called SS7887SE.DXF. This is a sample Ordnance Survey Land Line file that we will be using for this exercise.
You will be invited to enter the Units and a Scale. Sometimes you will be supplied CAD drawings in mm. In the example here use metres.
Both Scale and Units are important so do not ignore them. In n4ce all text is drawn in mm to a reference scale. In the example selected here the scale should be set to 1250.
Importing a DXF File
If you are opening a drawing from an Architect, it’s likely to be in mm. If you units of metres, then all your distances will be 1000x too large. The ruler bar is useful here.
Press OK and the DXF file will be imported into the Project
Imported CAD Showing Layers in the Viewing Window
Imported DXF File Viewed in the CAD Editor
Note When importing CAD files, a user defined Filter is available. This allows the filtering out of unwanted layers, changing Pens, Styles and Layer names. This is useful with OS Landline and Superplan files. Both Landline and Superplan file formats are being phased out, replaced with MastermapTM.
CAD data can be imported from DWG, DXF, DOT or Mastermap files. The DOT file is an internal AiC format used in previous DOS packages like PS3 and 4CE and supports all the data likely to be required in a survey, including coded points, symbols, CAD, DTMs and Groups.
CAD layers used will appear in the Display Window, showing number of elements, XY Extents, Status and if the layer contains 3D data. Several right click menu options are available here.
Individual layers can be viewed graphically using a Quick Viewer, by highlighting the layers of interest in this Display window and selecting the Camera Icon. No editing is available here.
If you wish to edit or create elements you go into the CAD Editor by focusing on the CAD folder and selecting a Camera Icon.
The CAD Editor has 5 major user interface tools, namely Menus, Icons, List Boxes, Input Boxes and Hot Keys.
Hot Keys and Icons act as short cuts to menu options. Both will be seen in menus, where they apply. An example of this is in the View menu shown above.
Note You can create your own personalised icon bars - see Customized Toolbars, but remember to Save otherwise they will be lost.
The panel on the left contains Edit Parameters which are used in the Draw options. If you need to draw detail to a fixed size or move detail by fixed amounts, fill out this panel. In the example being shown here, Relative Draw has been chosen, requesting dx and dy offsets.
CAD Layering Icons
CAD Drawing Defaults
The Icon Bar shown above has List Boxes that control the attributes attached to elements. The Current settings will be shown and used when plotting any new elements or changing the attributes of previously drawn elements and include Layer Name, Pen Colour, Line Style, Point Style and Text Style. Additional attributes will be attached to Points and Text which include size and justification.
Note: Text is defined with a Windows Font at a Size that is in mm at the current Object/Plot Scale and a justification.
When you hover over any Icon or List Box, with the mouse cursor, a Tool Tip appears giving you an indication of the tools function.
Whilst all the features of the CAD editor are important it is the Pick, Lock and Draw list boxes that provide extra control.
Pick, Lock and Draw List Boxes
Note Pick and Lock are also used in the Model editor.
Pick is used to select elements for edits such as move, delete, copy or change. Options include Element [SHIFT+ALT+E], Rectangle [SHIFT+ALT+R] and List (Pro & Des) [SHIFT+ALT+L].
Lock is how you attach (or snap) to elements already plotted. These include the following options, with [Hot Keys].
* Free [F]
* End [E]
* Mid [M]
* Near [N]
* Intersect [I]
* Centre [C]
* Quadrant [Q]
* Symbol [S]
* Point [P]
These Lock options are tied to the cursor box size which can be adjusted using the [SHIFT]+[<] and [SHIFT]+[>].
Locking is further controlled by the Must Lock [K] and 3D Lock [Z] Icons. If these are active (pushed in) they will control the picking of elements. A beep will indicate a positive or negative selection.
Draw is used to control positioning of detail. The options are:
* Locate [L]
* Relative [R]
* Polar [P]
* Bearing [B]
* World [W]
* Axis Lock [A]
* Hz Lock [H]
* Vt Lock [V]
If you’re using options that require type data, the Drawing Parameters Input Boxes will become active. By pressing the Create button in the Parameters panel or Return on the keyboard, these values will be applied.
The Edit Icon bar is very useful. The first two icons are Undo and Redo Icons (multi step). The next three Icons are Delete, Move and Copy.
Edit Icon Bar
The last icon is Show and is used to query an element, as seen below. You could of course use this to query CAD detail and copy coordinates to an Excel spreadsheet. But is there a better way?
Showing the Attributes of CAD Elements
The results of the query appear in a Rich Text editor.
Note If you wish to create your own Icon Bars, go to the View menu and explore Toolbars. But don’t forget to Save the changes, otherwise you will not be able to recall these the next time you run n4ce.
- Back to the exercise. Let’s demonstrate Backcloths. Select the CAD folder SS7887SE and go to graphics.
Now select the first Backcloth icon. This will present you with the Backcloths selection dialog box.
Backcloth Selection - Images
Select the Image tab and then press the Insert button. You will be invited to navigate to a folder and select a file. Whilst many different bitmap formats are readable, a special file format called ECW has been developed, with a coordinate reference (georeferenced).
Select the file 12485.ecw and press the Close button. This image has now been attached to this project but still needs moving over from the Available to the Selected window. Press the OK button to see the photo image behind the OS vector drawing.
OS Plan and Photo Image Superimposed
- Close the CAD graphics window and return to the Project Manager. We will use a CAD Backcloth to extract coordinate data for setting out.
Focus on the CAD layer called G8010001 (BUILDOUT) in the Display Window and select the Camera Icon. You should see building outlines, as shown below.
CAD Layer G8010001 (BUILDOUT)
Return to the Project and using the right click options in the display window make the status of G8010001 (BUILDOUT) Current and turn all the others Off. [CTRL+A] will highlight all the layers. Right click menu option Status to do this.
- On the Project Tree create a new Model folder called Buildings at a scale of 1250. We will create coordinates for these outlines.
Create New Model Folder Called Buildings
Focus on this new folder and note that there are no coordinates in the Grid on the right-hand side. Select the Camera Icon.
Use the Backcloths icon and move the CAD SS7887SE data folder from Available to Selected. If necessary, Zoom to extents.
Go to the Points-->Generate menu and select the Lines option. This will allow you to generate points along CAD lines, depending upon the Pick option that is selected. As you can see, other options are available for different element types.
Generate Points From CAD Lines
You will be invited to enter a code and other details from the following dialog box.
Selecting Generate Points From CAD Lines Options
Using the Element pick option, select a number of building outlines, then return to the Project Manager to view the Co-ordinate Grid (Spreadsheet). Points will appear, as shown below.
Points Appearing in the Buildings Model
Selecting CAD Outlines
- From the Buildings grid model highlight the first building (BD00), right click over the highlight and select the Export option. Use Normal with Save as Type set to CSV, enter the name Building.
Selecting the CSV Export Template
You can create your own CSV Template. This has an interface similar to elsewhere in n4ce.
Setting your Own CSV Filter
CSV files can be loaded into Total stations or GNNS receivers, but make sure you have set the correct format.
Summary of Exercise 7
CAD was covered in further detail here. As you saw in Exercise 6, CAD is a very powerful tool in n4ce. The Modes options Pick, Lock and Draw options were introduced as were Hot Keys.
A fundamental feature of n4ce was introduced, namely Backcloths. This was demonstrated with an OS Landline file against the backdrop of an Aerial Photograph. CAD Filters was mentioned which allows the filtering out of unwanted layers, changing layer names, colours and line styles.
Generating points from CAD was demonstrated using Backcloths using the Co-ordinate options. It was noted that some CAD elements may be in 2D. Not covered here was the ability to use text elements in a CAD drawing to recreate levels in a 2D CAD drawing – try this for yourself.
Further CAD extraction options are available with the Pro & Des editions, using models and being more selective in choice of CAD element.