ENG1021 Spatial Communication in Engineering

ENG1021 – Spatial Communication in Engineering

Table of Contents 1. Hand Sketching Overview & Guide ............................................................................................................................... 2

2. AutoCAD ........................................................................................................................................................................ 6

2.1 Drawing in AutoCAD................................................................................................................................................ 6

2.2 AutoCAD Shortcuts ................................................................................................................................................. 7

2.3 Other CAD Considerations ...................................................................................................................................... 7

3. 3D Modelling & Visualisation ........................................................................................................................................ 8

3.1 3D modelling with Sketchup ................................................................................................................................... 8

4. Introduction to GIS ...................................................................................................................................................... 10

4.1 Introduction .......................................................................................................................................................... 10

4.2 Wk7 Prac ............................................................................................................................................................... 11

4.3 Wk8 Prac ............................................................................................................................................................... 12

5. Spatial Data Analysis in GIS 1 ...................................................................................................................................... 13

5.1 Spatial Analysis and Modelling ............................................................................................................................. 13

5.2 Wk9 Prac ............................................................................................................................................................... 14

5.3 Wk10 Prac ............................................................................................................................................................. 15

6. Digital Terrain Analysis in GIS ...................................................................................................................................... 19

6.1 Hydrological Characteristics Analysis .................................................................................................................... 19

6.2 Visibility Analysis ................................................................................................................................................... 19

6.3 Wk11 Prac ............................................................................................................................................................. 20

7. Exam Summary ........................................................................................................................................................... 23

7.1 GIS Recap (What you should be confident with) .................................................................................................. 23

7.2 What to revise for Exam........................................................................................................................................ 23

ENG1021: Spatial Communication in Engineering Page 2

1. Hand Sketching Overview & Guide

▪ General Points

- Use light construction lines to construct a proportioned bounding box

- If given grid, count the grid to get proportioning (using the 1:1 depth axis ratio)

- If no grid given, use trammel to estimate the length ratios (will always be an integer) to get proportioning

- All drawings are to be parallel projections for ENG1021

Planar Projections

o Isometric - Axis are at 120s (30o from horizontal) - No face parallel to projection plane -

o Oblique - Principle face parallel to projection plane - Use Cavalier projection (1:1 depth axis ratio) when drawing

o Multi-view - Only one object face is visible in each view - Each face is parallel to principle plane - Front face chosen by longest length shown - Use mitre line (45o line) to get proportion correct, used to transfer features

Other Multi-View examples

Notes: 1) Make sure you show all hidden & centre lines when drawing multi-views


Generating a Section View Sketch Example (Step-by-step)

- Given the top and right views of an object, draw the front section view

1) Use parallel construction lines to locate object features in the front view.

2) Draw the front view. 3) Identify the surfaces being cut Apply section lining or hatch pattern (except for thin features)

Other examples

Notes 1. A hatch pattern is applied to surfaces on the cutting plane (Don’t hash pattern thin features, as it complicates the depths) 2. Cross-section Arrows indicate the viewing direction 3. Section view should show hidden edges, centre lines & visible edges


2.2 AutoCAD Shortcuts

AutoCAD Shortcuts

SYNTAX/Tab Description UNITS To change units

NAVBARDISPLAY Activates the navigation bar display on the right side of the window (shows pan, zoom etc.)

LINE Specify the points to draw a line Type ‘0,0’ in the command line to specify the first point Type ‘90,0’ in the command line to specify the next point Type ‘@90,0’ to draw line from a selected point to 90,0 Use ‘tab’ to toggle length & angle To change a lines properties, press DOWN arrow key

ARC Creates an arc using 3 points Use lengthen to stretch the arc length w/out changing the radius Use radius to adjust the arc radius

PLINE Polyline Type ‘A’ for Arc Type ‘S’ for Second Point Type ‘@[across, up/down]’ to specify next point

UCSICON To show or hide the coordinate icon in AutoCAD

UCS To change the origin of the coordinate system

FILLET Rounds and fillets the edges of objects Type ‘R’ for radius

CHAMFER Bevels the edges of objects

DS Opens drafting settings, tabs include: Snap & grid (Snap on & grid on) Polar Tracking (changes angle resolution) Object Snap (object snap modes: endpoint, midpoint centre etc.)

ORTHO (F8) Orthographic mode, drawing only along major axis

OSNAP Object snap

TRIM Trims back intersecting lines (Select lines around the section you want to delete)

EXTEND Extends perpendicular lines to intersect

OFFSET Specify the offset distance

MIRROR Mirrors selected objects

ARRAY Mirrors selected object into column & row array Segment array (to create rows/columns of copies) Path array (to distribute object copies along a line)

HATCH To add patterns or gradients to a closed object Can change “associative” to update hatch boundaries

LWDISPLAY To show/hide line weight (or go to customization, bottom right ribbon)

DIMSTYLE To change angle or length precision Can be used to change scale of dimensions (DIMSTYLE > fit tab > overall scale)

OSNAP To snap to objects Notes

1) Use shift + select to de-select objects

2) Press ESC to cancel tool or stop drawing & Press ENTER to re-enable the previous tool

3) To enable a recently used tool, use UP arrow key (browse for it, then ENTER to enable)

2.3 Other CAD Considerations

▪ LAYERS:

- Use layers to group objects by category

- Zero layer is default, create different layers to organise objects

- Can turn on/off, freeze/thaw (AUTOCAD cant see it, improve comp performance) or lock/unlock layers

- Isolate: shows only selected

- From property manager: Change colour, line weight & transparency

- Can assign objects to any layer

- There exists naming conventions i.e Standards on assigning layer names in indunstry


4.2 Wk7 Prac

Task 7: Introduction to ArcGIS & Map Projections

Starting ArcMAP Open ArcGIS Map

Adding/Removing Spatial Data sets

Drag .shp files onto table of contents Make sure you have blank empty map to start

Saving and Opening a Map Document

- The file name extension (.mxd) is automatically appended to your map document name. Note that the data layers are not stored in the .mxd file

- If you copy the map document to a disk, you must copy all the dataset files used in the ArcMap project to that disk as well

To open, go to catalogue (windows > catalogue > connect to folder)

Layout view & Data View See bottom left icons to change views Use layout view to add: - Titles, legends, scale bar, text box & north arrows (Insert > legend…) - To edit any item, double click it - Change to landscape (file > page and print setup….) When in layout view to change size of data: Properties > size & position > then play w/ zoom in ribbon

Layers Right click layer names to edit properties (this will change legend items on the fly) Can also remove layers Can also set layer order: Drag layer names to change order (some layers may cover others)

Exporting Maps File > export map > save as .pdf

Saving & Relative Paths ArcMap project files are saved as .mxd Relative Paths: - Must make path names relative: File > Map Document Properties.. > Tick ‘store relative pathnames..’ > Apply - Save the .mxd file in the same directory as the data

Manipulating Symbology Right click layer > properties > symbology > Categories

Data Frames To create new data frame: Insert tab > Data Frame (to create a new empty data frame in the map) Must ‘Activate’ data frames (current active data frame will appear in bold): Left click data frame > activate

Setting Layer Order Drag layer names to change order (some layers may cover others)

Measuring Distance & Areas

Use the measure tool in the ribbon

Map Projections: To Identify the geographical coordinate system associated with a data layer: Layer properties > Source tab To Define a geographical coordinate system: ArcToolbox > Data Management Tools > Projections and Transformations > Define Projection To Transforming the geographical coordinate system: ArcToolbox > Data Management Tools > Projections and Transformations > Project In the Project dialog box: input = dataset or feature class i.e your .shp file’ output = (store in personal geodatabase) output coordinate system = choose required ‘Output coordinate system’


5. Spatial Data Analysis in GIS 1

5.1 Spatial Analysis and Modelling

Spatial analysis and modelling refers to a set of methods used to examine, summarise, manipulate, analyse and

interpret spatial data to discover, understand and predict spatial patterns, spatial relationships, trends and their

underlying causes:

• The distinct feature of spatial analysis compared with classic statistical analysis and other methods is that its results change when the

locations of the analysed geographical phenomena change

• Spatial analysis and modelling provides a means of turning spatial data into useful information of knowledge

Spatial analysis and modelling techniques are divided into 7 categories:

No. Category Tools

1 GIS fundamental

operations

o Spatial query

o Reclassification

o Geometric measurements

o Buffering and proximity measurements

o Overlay

2 Spatial

interpolation

o Inverse distance weighted

o Spline

o Trend surface

o Kriging

3 Surface analysis o Slope

o Aspect

o Curvature

o Visibility

o Profiling

4 Spatial statistics o Spatial descriptive statistics

o Spatial inferential statistics

o Spatial regression

o Spatial clustering

5 Network analysis o Finding shortest path

o Finding closest facilities

o Finding service areas

6 Spatial decision

analysis

o Multi-criteria analysis

o Multi-objective optimisation

7 Spatial modelling o Cellular automata

o Agent-based modelling

o Weights-of-evidence

Notes:

1) Need to understand how these tools work & why/when we'd want to use them (also need to know what inputs are required for these tools & what are the

requirements/data structure & the analysis output). This will be covered in sections 9-12

2) Most of these tools only work w/ either raster or vector data (overlay works w/ both)


5.2 Wk9 Prac

Tutorial Tasks

Query by Attribute

To build a query: Layer > ‘Open attribute table’ > Table options button > Select By Attributes - Just use the buttons on the menu to compose the selection expression e.g., "AREA" >= 3001.8695 AND "AREA" <= 9969.29615 To add field: Table options > Add Field… - We can then select by attributes (as above) and use Field Calculator to assign values To change the legend symbols used: Layer Properties > Symbology tab > Categories > Unique Values > Change value field & ‘Add all values’

Query by Location

Select by Proximity & Adjacency: Proximity (how close or far apart the features are) Adjacency (features that share the same boundary) Finding points near lines: Selection tab in main ribbon > Select by location > Select features from…. Finding features that intersect other features: 1) Select by Location: Selection tab in main ribbon > Select by location > Select features from…. Specify target layer (what you want to select) then Source layer (the feature we want to intersect) 2) Select by Adjacency: Manually select a feature > Selection tab in main ribbon > Select by Location > Selection method = select features from > Set target & source layers > Spatial Selection Method of Target layer(s) features = touch the boundary of source layer features

Reclassification To reclassify/aggregate classes to a few main categories: 1) Add a new field (also called a new item or column) 2) Select the appropriate records using query builder 3) Assign appropriate values to the new field for these selected record 4) Repeat steps 2 & 3 until all records are processed To change the legend symbols used: Layer Properties > Symbology tab > Categories > Unique Values > Change value field & ‘Add all values’

Length & Area Measurement

Measure length and area on the map: Click measure tool on main ribbon (Measure Line, Measure An Area & Measure A Features tools Calculate geometries of features and adding them to the attribute table: Layer > open attribute table > Add field… > Calculate Geometry…. (repeat this for Area, perimeter & centroids) Note: Calculate Geometry tool can only be used for vector data Calculate areas in raster: Open Layer Attributes table > Add field (Area) > Field Calculator > [Count]*cell size of raster* cell size of raster

Buffering Buffering with a fixed distance: Geoprocessing tab on main ribbon > Buffer > Select input (what you want to buffer around) > Set linear unit to x meters > Side type = FULL & Dissolve type = ALL Buffering with variable distances: Layer > Open Attribute table > Add Field.. > create buffer distance field called ‘width’ Geoprocessing tab on main ribbon > Buffer > Select input (what you want to buffer around) > Check Field, and select Width (FULL site type & dissolve type ALL)

Generating Distance Surface

To enable the Spatial Analyst extension: Customize tab > Extensions… > Check Spatial Analysist Generate a physical distance surface: ArcToolBox > Spatial Analyst Tools > Distance > Euclidean Distance > Select input feature (the feature we want to create our distance surface from) (takes ~1min to load) Generate a cost distance surface: ArcToolBox > Spatial Analyst Tools > Distance> Cost Distance > Select input feature & Select costOnSlope as the input cost raster

Creating Least-Cost Paths

Generate a cost distance surface and a direction raster: ArcToolBox > Spatial Analyst Tools > Distance> Cost Distance > Select input feature & Select costOnSlope as the input cost raster > Output Backlink Raster (use the same directory as output distance raster and add “_backlink” at the end of the file name) Calculate the least-cost paths: ArcToolBox > Spatial Analyst Tools > Distance > Cost Path > Select input feature (i.e., the other end of the path) > Select the cost distance raster and the cost backlink raster created in the last step as the input cost distance raster and input cost back-link raster


7. Exam Summary

7.1 GIS Recap (What you should be confident with)

1. Geographical space concepts: geographical coordinate systems, map projections (reprojecting) 2. Spatial data model & spatial data management: vector/raster data models and topological relationships… 3. Spatial data input & manipulation: spatial data transformation (e.g. geo-referencing), spatial data capture (e.g on-screen digitizing), and

spatial data editing (How to correct errors e.g. rubber sheeting, affine, topology editing…)

4. Spatial data analysis: spatial data queries, data reclassification, surface analysis, spatial interpolations, buffering (& variable buffers), map

overlay (intersect/erase/update etc.), map algebra (raster calculator) and cost-path analysis. 5. Digital terrain analysis: hydrological correction (fill to correct sinks), terrain attributes (flow direction > flow accumulation > drainage

network > catchment area) and visibility analysis of spatial data

6. Spatial visualization: cartographic representations & map designs (all maps produced should follow the ISO layout)

7.2 What to revise for Exam

Exam typically has 5-6 questions & is 2 hours, exam questions are often similar to assignment questions. My advice is to allocate a full hour to

GIS questions, maybe even more than an hour if you’re a fast drawer & confident with CAD!!

Q1-2 = Hand drawings

- Asked to produce isometric or oblique views, multi views, cross-sections etc. - Drawings given on grid paper to count grid to get proportioning (then re-draw on blank paper using tremmel)

Q3 = AutoCAD

- Given a drawing to replicate (i.e your given its shape & dimensions)

- Must follow dimension styles

Q4-6 = GIS

- Spatial data analysis (i.e calculating cost surfaces) & Digital terrain analysis (watershed functions)

- Questions given here are typically similar to assignment

Documents

ENG1021 Spatial Communication in Engineering