These notes are designed to guide those landscape designers moving to CAD for the first time.
We provide an introduction to the world of computer-aided landscape drafting and compare the process to hand drafting.
Drafting on paper
When drafting by hand, it is usual to take a clean sheet of paper of appropriate size and put it on a drawing board (table) along with your scale ruler.
You then think about the design, the views, and the scales you will use to convey the design effectively. Finally, you put pen to paper, selecting drafting pens of varying thickness as you work. You work with a scale ruler all the time.
Sheets in Australia and Europe usually use the ISO A series – A0, A1, A2 etc. The B series of sheets – B1, B2, B3 and B4 – are less commonly used and reserved for US design work.
Pens
Most technical drafters use special drafting pens, such as those made by the Rotring company, to emphasize parts of the design. These pens have an accurately defined pen nib width (line thickness). 0.25 mm, 0.35 mm, 0.5 mm, 0.7 mm, 1.0 mm etc.
Why this emphasis on line weights?
Most drafting tutors insist that you use these special pens and construct your drawings with varying line weights because your drawings will have ‘depth’; drawings will have good definitions and can be easily read and interpreted.
A 0.5 mm Rotring pen has a red ring around it to help you identify the thickness of the particular pen. In Australia, many drafters use the same system when creating CAD drawings. If a line in the drawing is red, this implies (when it comes to plotting) a 0.5 mm pen will be assigned. Colour can be associated by setting a colour property to an individual element, like a line, or by associating colour with the layer on which the line is located. If you are operating in an environment where the Imperial system is used (feet and inches), the thickness will be a different unit (fractions of an inch), but the principle is the same.
Experienced drafters often lay a drawing out with a fine pen and then ‘go over’ different parts with a thicker pen for emphasis. This is good practice and can be mimicked in the CAD environment.
Drawing aids
Various aids, such as set squares and rulers, are often used to assist when drafting by hand. Some of these devices are ‘built-in’ to the drawing table (sometimes called drawing machines). The settings on these drawing machines can usually be altered, for example, by changing the drafting angle.
CAD software such as gCADPlus contains the equivalent of a drawing machine, and you can change settings to suit your purpose; for example, you can easily change the drafting angle and many other settings.
Rubber stamp shapes – symbols/blocks
If the same shape(s) is used repeatedly in your drafting, for instance, chairs, desks, trees and shrubs, bolts, flanges, etc., then it is likely that you will have made templates of these shapes so that you can place copies of your standard symbols into drawings. The same applies in the CAD environment, where we can easily make and use standard symbols.
These symbols are called BLOCKS. If the drafter needs to ‘stamp’ shapes into the drawing, these stamps (called blocks by gCADPlus and AutoCAD, but cells, symbols, or stamps by other CAD programs can be called by instructions (Commands)) enable the complex shapes to be easily inserted.
Drafting using a computer – ‘CADDing’ about?
A drafter using a CAD system works much like a ‘manual’ drafter. However, you don’t pull out a piece of paper first, think about scales, and start to draw; you concentrate on building the design immediately (creating a full-size model of your design on the computer). This is done by accurately entering data describing the design into the ‘drawing space’—sometimes called the drawing editor.
A mouse, keyboard, or other input devices can be used—light pens, touch pens, trackballs, photography, and digitizers can all be used as input devices. The ability of CAD software to incorporate images from phone cameras is beneficial.
After the drafter has finished creating the design (the model), the drawing sheet with its title block information is inserted, often in the ‘paper space’ or the ‘presentation’ area.
Remember that the designers of CAD programs such as gCADPlus have tried to make the program mimic how drafting work is done at a conventional drawing table. The correlation is robust indeed. If you remember this, it is easy to avoid initial confusion, mainly by introducing new terminology. When learning CAD, ask yourself, “How would I do this on the board? There must be an equivalent somewhere in the software.”
Viewing your design
Just as you do when drafting by hand, a CAD system allows you to work on different parts of the drawing sheet at various times. For example, the drawing might be viewed at close quarters while constructing a detailed design and then viewed further away while composing the design on the sheet.
The developing CAD drawing is viewed on some display monitors. So, the software (the CAD program) and hardware (the computer) record the geometry of the design drawing and save the growing bank of information about the drawing in a database.
CAD software such as gCADPlus, which runs under Windows, can simultaneously display the design on one screen and various tool palettes and plant databases on two monitors.
The drawing is a database.
It is most important to recognise that CAD programs such as gCADPlus use a coordinate system to record the location of entities in the drawing. These coordinates are stored in the database describing the drawing. Indeed, it is possible to interrogate the drawing and obtain lists of (say) pieces of equipment that have been specified.
The database (the drawing) may be edited (changed) at any time, and the screen may be refreshed to update the drawing (design). Once the drafter is satisfied that the drawing is complete, the image is sent to various ‘hard copy’ output devices, including printers/plotters and plotters. The drawing may be printed (plotted) out at multiple scales. Once printed, the drawing is usually saved in electronic form on disk.
CAD drawings can contain layers
Numerous (transparent) overlay sheets will likely be used in CAD drawings to incorporate more information. By turning layers off and on as needed, several drawings can be made from a single drawing.
CAD drawings are easily edited
If mistakes are made in a hand drawing, they are removed using an eraser. CAD software has an ERASE command. Many entities can be removed at the same time. There is also a handy UNDO tool.
If you make a mistake, there is no need to start over. Don’t erase the drawing; UNDO it to the correct point, and start again.
Remember that COPY is an editing command. Editing is not all about correcting your mistakes—we use the many and varied editing commands to build up our geometry!
Precision. In addition to removing mistakes, you can also move (say) a wall 600 mm in a particular direction, change the layer an entity is located on, etc.
Printing
When the drawing is finished, the final edited drawing is plotted (printed) at any scale you want and on any size paper. It is then stored (filed) in a plan cabinet. In summary, the CAD process mimics the hand drawing process.
Learning to use CAD software – some advice
It helps when learning CAD to realise that gCADPlus software mimics the ‘hand drawn’ drawing process. Instead of using a pen or pencil as a drafting tool, the pointing device (a mouse) drives an ‘electronic pencil’ around the computer screen. The screen is analogous to the drawing board. The pencil is positioned metaphorically and then lowered onto the electronic drawing board. Special instructions are then issued to produce the entities (lines, arcs, circles, etc.) placed in the drawing. The significant advantage of this process is that it is not necessary to draw shapes like circles, ellipses etc., these shapes (and even more complex ones), are placed into the drawing. The CAD program creates the shape perfectly every time, locating it precisely.
When operating at maximum productivity, a CAD drafter becomes an assembler of pre-drawn parts.
‘Real world’ units
Most drawing involves producing plans. A plan is a collection of lines representing actual objects, which can vary in size. They may be doors or windows on a house plan, flanges or details of welding joints in a mechanical drawing, circles representing trees and shrubs in a landscape plan, or sketched lines representing the boundaries of a blood capillary as seen down a microscope.
The objects have actual dimensions. The block of land on which a house sits might be rectangular, perhaps 35,000 mm (35 m) by 28,000 mm (25 m). The door in an architectural plan may be 600 mm wide and 1900 mm high, the window 2700 mm by 1000 mm, the canopy diameter of a tall tree in a survey plan 35 meters or something as small as a blood capillary, 6 micrometres wide. Each item has dimensions that mean something to the designer in the real world!
When you draft by hand, you constantly use a scale ruler (1 mm represents 100 mm – 1:100; 1 inch 8 ft – 1:96, etc.) When drawing with gCADPlus, you do not draw to scale; you construct the drawing in drawing units. In gCADPlus, these drawing units are ‘set’ equal to ‘real world’ units. This is a ‘mental’ setting in the mind of the designer. If the cursor (pointer) on the screen moves one drawing unit, this is equivalent to a movement of one unit in the designer’s world.
Everything in the building trade in Australia is measured in mm, so one drawing unit equals 1 mm. The window is 2700 units by 1000 units, i.e. 2700 mm long by 1000 mm wide, no more, no less.
If you were a surveyor, you would probably work in meters. A landscape designer would use the SCALE command in gCADPlus to scale the drawing so she could work in mm.
Forget scale rulers
Conventional drafters constantly use scale rulers and must be aware of the scale they use. gCADPlus users suffer no restriction; they draw in ‘real world’ units where the drawing unit equals the actual unit used to size the object. Experienced manual drafters must forget the traditional way of doing things and, metaphorically, ‘throw away’ their scale rulers. Many new CAD operators who have previously trained as manual drafters become confused when first seeing a CAD system because they are not now required to work to a scale.
If you measure a screw 6″ long with a ruler, then draw it 6″ long. If you have a piston 2″ in diameter, then draw it 2″ in diameter. If you fail to draw things the same size as in the real world, you will have endless trouble with dimensions, etc. Never scale a drawing up or down. Scale title blocks up and down all you want, but not the drawing itself.
Scales and plotting
It is only at the final assembly of the drawing on the display sheet (border sheet) that one considers scale. We might take the drawing of (say) a plot of land (the site boundaries), insert a drawing of house plans into it, and finally insert and scale up the drawing sheet around the block of land at a suitable scale.
If a landscape designer had a large plotter, it would be possible to plot a site plan at a scale of 1:1 and use it as a template for laying out the foundation and brickwork.
This lack of concern about scale when using gCADPlus is the significant difference between CAD drafting and conventional methods.
Note: The approach to preparing CAD drawings outlined above is not the only one used, but most CAD drafters work ‘full size’. Rather than inserting part drawings into a sheet of real-world size, some (a very few) drafters ‘scale down’ the parts as they bring them into the presentation sheet and then plot the sheet 1:1. The danger with this approach is that the parts have been scaled down and cannot be stretched and re-dimensioned later without taking into account this scaling factor. You really must learn to draw full-size when using CAD!
CAD drawings are very accurate
CAD programs such as gCADPlus keep a database describing the developing drawing that is accurate to 16 decimal places (floating point arithmetic). The accuracy of your drawing is limited only by the accuracy of the printer or plotter you use to produce the printed plan.
The Advantages of Computer-Aided Design
At this point, beginners always ask about the benefits of using a CAD program. Some of the major benefits are listed below.
Speed
I am sure you want to improve the speed and efficiency of your drafting. Rest assured that once you gain the necessary skills, you can complete drawings more rapidly and neatly using CAD than by hand.
The main reason for the increased speed is that much drafting is repetitive – think of the amount of lettering found in most drawings. Lettering is repetitive and more efficiently done by typing the required characters and letting the CAD program insert them rather than placing them by hand using stencils. This applies even if you are not a very fast typist – ‘hunting and pecking’ is quite OK for a CAD operator.
Many other drawing tasks are also repetitive; the architect designing a multi-story building uses the same base plan at each level of the building and many of the same fixtures and fittings in each room on a floor, simply arranging components differently to produce the desired design; a designer of printed circuit boards uses many of the same silicon chips in a design, while a landscape designer will usually use many instances of the same species of plant in a planting plan.
Thus, CAD shines when standard components are inserted into assembly drawings.
At its most sophisticated, CAD software may even be used to build complex drawings simply by assembling a whole series of smaller drawings. If you learn to use gCADPlus templates, much of the heavy work can be done before you put pen to paper or, more accurately, the cursor to the screen.
CAD drawings are easily edited.
Since CAD drawings are easily changed, ‘going back to the drawing board’ is not a phrase to be feared. In design work, minor adjustments to a drawing are often necessary —moving a wall, removing a window, altering a layer on a printed circuit board, changing the size of bolts used in a mechanical assembly, etc. These changes are difficult to quickly and neatly achieve using conventional methods.
A CAD drawing may be plotted at different scales.
The same drawing may be plotted many times at different scales, and other views of the drawing can be shown on a single presentation sheet. For emphasis, different colours or thicknesses of pens can be used in plotters.
Semi-automatic and associative dimensioning is possible.
Since objects are drawn at full size, dimensions are easily inserted into drawings because they are taken from the “model” itself. These dimensions change automatically if parts of the drawing are stretched (when what is known as associative dimensioning is turned on).
While working on a design for a small courtyard, we wanted to change the length of a wall. A linear dimension had already been applied to the wall, and we show that the STRETCH command can be used to alter the size of the wall and the dimension itself in one step.
It bears repeating that everything you draw with your gCADPlus software must be fully sized. This means that any time you enquire about part of your drawing (using any of the enquiry group of commands – DISTANCE, LIST, ID or AREA), the software ‘spits back’ values that mean something to you as a designer. We emphasized this many times in this set of notes, but you must keep reminding yourself of it when you first work with gCADPlus. This concept of ‘drawing full size’ is a significant change for many people and can be most disconcerting if you have long been used to producing paper drawings by hand on a drawing board.
Information can be extracted from drawings.
gCADPlus has tools that enable non-graphical information contained within the drawing (botanical name, common name, code, number of plants used, etc. to be written to a file, which can subsequently be read by other programs such as Excel to prepare bills of materials
To sum up, CAD software helps you build a computer model of what will be constructed in the garden space. There should be no surprises when the construction team goes on-site!
gCADPlus software is an example of a ‘command-driven’ program. There are various groups of instructions for creating drawings. Many instructions (commands) exist to get a new sheet from a FILE cabinet. Similarly, there are many commands to DRAW different entities, DISPLAY the drawing, EDIT the drawing, define and use BLOCKS as templates, create and switch between LAYERS, etc. Drawing utilities analogous to the rulers and squares mentioned above may be used. It is possible to PLOT the drawing on paper and to FILE the completed drawing.
It is helpful to think of a CAD program as a set of drawers in a file cabinet, each drawer containing a specific set (group) of commands such as DRAW, EDIT, DISPLAY, etc. Within the DRAW group, you will find a LINE command, an ARC command, a CIRCLE command, and so on.
Do I need to learn CAD commands by heart?
As we have said, the instructions given in gCADPlus for placing elements such as lines and circles into the design space (the drawing) are called commands. There are many commands. Beginners quite reasonably ask at this point, ‘Do I need to learn the commands by heart, or can I rely on clicking on a toolbar icon on the screen or menu item to call the instruction I want?’ The answer is no, everything is available on a drop menu, toolbar or can be typed into the drawing. The choice of how to do it is yours.
How many commands exist in gCADPlus?
There are more than 200 commands available to you. Indeed, you do not need to learn all of them. It is said that a typical user will use 20% of commands 80% of the time. It’s knowing how to use the 20% properly that’s important.
So, besides attempting to show you how to use enough commands to build a CAD drawing in this course, we will place considerable emphasis on choosing the appropriate group of commands, focusing on why a particular command is used.
Set up gCADPlus for ease of use.
The installation process for gCADPlus typically leaves a desktop shortcut to the program. An appropriately configured shortcut can help you get more out of your gCADPlus software. We will deal with that in a later session.
Landscape designers who wish to move from hand drafting landscape plans to doing the same using CAD drafting face some challenges. It is often easier to see what’s involved rather than read about it.
This movie introduces the world of computer-aided landscape drafting and compares the process to hand drafting. To sum up, when using CAD to produce your designs rather than hand drafting:
- You work full size when designing. Concern about scale comes later.
- Use the mouse or touchpad to zoom in and pan about to display different views of your design.
- Keep the properties visible while drafting. They display the accurate size of the entities selected and other information.
- You don’t need to draw every symbol from scratch. An extensive set of pre-drawn symbols are available.
- The SCALE tool can be used to change the size of a selected symbol.
- A drawing can contain layers. These can be switched on or off, displaying more or less of the design. This is especially useful when printing a design.
- Symbols can be associated with particular plant species and displayed in the properties box when selected.
- It is possible to automatically generate a plant schedule showing the species name and the exact number of all plants used in the design. If changes are made, the plant schedule can be refreshed and will show count changes.
Tip: The movie naturally focuses on using our landscape design application (gCADPlus). However, we hope the notes are sufficiently helpful for those using other CAD programs, such as AutoCAD and DraftSight. These alternative landscape applications work similarly.