ArcGIS for Geoscientists

Transcription

1 School of Geosciences ArcGIS for Geoscientists R. Armit & T. Carmichael

2 GIS A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of spatial data. From tracking diseases to vectors to mineralisation. 2

3 GIS Gocad Iogas 3

4 The Package ArcMap ArcScene ArcGlobe Online guide available at: version 10.0 help version 10.1 help version 10.2 help 4

5 Modern light table 5

6 Arcmap Lithologies and samples in Armit et al Mount Painter 6

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8 ArcScene DTM of northern Flinders Ranges 8

9 ArcScene flyins 9

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11 ArcGlobe 2.5 Million scale Australia Faults and Global seismicity for last 10 years. 11

12 ArcMap Practical data available at: 12

13 The interface 13

14 Major components of the Interface screen Table of contents Data Frame ArcCatalog ArcToolbox Identify features Attributes Attributes table The blue arrows 14

15 Identify features Data Frame ArcCatalog Table of contents 15

16 Attributes table Attributes ArcToolbox 16

17 The blue arrows 17

18 The dashboard Opening the arccatalog, Toolbox or TOC windows Panning and zooming Measuring and identify features Drawing not that same as editing (not spatially linked), however can convert 18

19 Setting up your project Define projection Add basemap Add data (different types) Georeference available images 19

20 You must make a choice of Datum and coordinate system for your project. Normally depends on scale and location of project. Making an error here can put your 100 of metres out to half the globe. Below is a brief summary of the Australian map grid systems. Spheroid Datum Projection WGS84 WGS84 World UTM (world) AMG66 ANS70 AGD66 UTM (local using zones) AMG84 ANS70 AGD84 UTM (local using zones) MGA94 GRS80 AFN / GDA94 UTM (local using zones) 20

21 Defining the projects projection 21

22 Base maps 22

23 Basemaps 23

24 Imagery in ArcMap already geo-referenced 24

25 Adding data Raster Types of data Raster Vector Table Table Date Easting Northing Location Lithology Measurement Strike Dip Dir Dip_Dir Mt 26/05/ Moornambool Pelitic East Face Schist S W 251 Vector Mt 26/05/ Moornambool Pelitic East Face Schist S W 110 Mt 26/05/ Moornambool Pelitic East Face Schist S W 251 Mt 26/05/ Moornambool Pelitic East Face Schist S E 100 Mt 26/05/ Moornambool Pelitic East Face Schist S W 218 Mt 26/05/ Moornambool Pelitic East Face Schist S W 250 Mt 26/05/ Moornambool Pelitic East Face Schist F Mt 26/05/ Moornambool Pelitic East Face Schist F Mt 26/05/ Moornambool Pelitic East Face Schist S W 92 Mt 26/05/ Moornambool Pelitic East Face Schist S W

26 Adding data many ways Dragging the file in. More complicated in Windows Ex with multiple file extensions 26

27 Rasters Common file extensions include: Tiffs, jps, png, gif, img Multi files like.hdr,.bil (band interleaved) Plug in required formats include geosoft.grd format Geotiffs and georeferenced tagged jpegs supported and easy to use Raster types in ArcMap 10 However as general rule: Raster that you require that colour values to remain Fixed are best imported as jpg, tiff or png. Gridded raster files such as grd, bil, ers will require colour ramp processing on Import. If the raster is georeferenced then it will often have a number of extra files that You will need to copy across to keep geo referencing info (e.g..aux. rrd). These are not visible through add data or arccatalog. One way to reduce file size is to keep rasters as raster database.gdb 27

28 Building pyramids and display types Nearest neighbour for rasters with text etc. Bilinear for gridded data eg. Geochem or geophysics 28

29 Transparency In the same window you can change The transparency of the layer. This is useful to visualise or merge two or more images. 29

30 Georeferencing rasters On published maps, the projection and grid values are normally provided 30

31 Georeferencing rasters Control points 31

32 Vector A vector is a dataset which is composed of points, lines and polygons, rather then individual pixels. By clicking Add data from the standard ribbon and navigating to a file, you can open a wide array of files. 32

33 Geodatabase pros and cons A geodatabase is a way to store a variety of different types of spatial data in the one location. You can also set an array of different rules and relationships between all your data. Depending on how deep into GIS that you are getting, a Geodatabase could be too involved as it is very time consuming. It also decreases the amount of interoperability (if you re dragging files between different programs) 33

34 Topology Topology, in terms of GIS refers to a set of rules and behaviours that model how points, lines and polygons relate to each other. When creating features in GIS, either topological or discrete rules can be used to define these features. In the following examples we will use discrete rules to create each of the different feature classes (e.g. points, lines and polygons) 34

35 Creating a point layer 35

36 Creating a point layer 36

37 Creating a point layer 37

38 Digitizing polylines is done in the same way that the creation of points, except that the end result is defined by a line, instead of a single point. The can be used to represent a large amount of geological data that is defined as linear. It is extremely important to use the style tool to make sure that you can visualise what each of your line represents. This will be covered later in this course. 38

39 Layers that are created as Polygons are initially added in the same way that polylines and points are. Polygons are used to define enclosed 2D areas. It is defined by a set of (x,y) co-ordinate pairs. 39

40 Create an initial polygon by selecting points on the map similarly to placing points or polylines, the program will join these points with straight lines. By using the Snapping Options from the Snapping menu, you can snap to another feature. 40

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43 The data you initially collect in the field will unlikely be in a format that you can directly import into a GIS package. The easiest way to solve this is to convert a table (usually a.csv file) into something more workable. Using GIS it is possible to turn field data, into manipulable, useful, information 43

44 It is vital that before you go out into the field, that you know what data you re going to collect and how your input table should be set up. What information do you need to record at each location? Do you have a comments section to record pertinent information? What coordinate system is my GPS in? Was my data input into my table correctly? (Have I qaqc d my data?) Are all my measurements in Strike and dip or dip and dip direction? Do my numbers make sense? Did I record them all in the same way? All of these questions (and more!) need to be dealt with before you try to import your data. Otherwise, any errors that you bring in will be involved in your interpretation. 44

45 Symbol rotation, level and the lyr file 45

46 Symbol rotation, level and the lyr file 46

47 Join and relate tables define the join based either on attributes, a predefined geodatabase relationship class or by location (also referred to as a spatial join). 47

48 Queries Spatially related Attribute related Combined queries Quick queries Exporting and subsampling from the query 48

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50 There are several important features of the query builder which can make your life infinitely easier. If you select an option from the Fields submenu and then hit sample (or all) you get the values that are present in that field. By using the Operators we can build a query which will highlight certain things. If we re working with text then its easiest to choose a value from the Values because it needs to be exact. The IF and AND functions can help highlight areas which have more then one characteristic that we re interested in. 50

51 By creating this query we can highlight only the features which are Silurian(Ludlow) and are Intrusives. 51

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53 Field calculator and calculating geometries Length, volume, area, azimuth, centroids and many more maths can be easily calculated. Open an attributes table (right mouse click a layer in TOC) and click attributes table. Click on a column heading or field. Click field calculator or calculate geometry 53

54 Calculate Geometry Allows simple area, length, centroid calculations depending on the data type. 54

55 Field calculator Allows for simple mathematical calculations to be made on the data (statistics a level up). If you need to more complex inter related calculations then use the ArcToolbox instead. 55

56 The layout window and map production Layout view Bookmarks 2 nd zoom controls 2 nd data frame Renaming for legend Grids Legend North Arrow Placement Clipping entire data Merged rasters Export types Issues with linework etc. 56

57 The layout window 57

58 Two zoom controls one for frame and one for data extent 58

59 Bookmarks Use this to define a fixed zoom area so if you need to keep looking at more detail and back out you keep the same extent for your output map. Massive time saver. Otherwise use blue arrows to go back a forth extents. Insert legend, North Arrow, scale bar Insert a second data frame Very good and automated frame extent on larger data sets e.g. for study location on country map etc. 59

60 Legend Use the L and R arrows to add which selected items you wish to add to the Legend and how many columns you want. Up and Down control the order for the legend. The rest of the legend wizard is stylistic options and this is up to you. You can also add labels for features from the labels tab in the properties of each layer. You can edit the legend, north arrow and scale after you have added them to the layout. Make sure you can selected the item you want to amend (blue corner nodes appear). Then right mouse click and go to the properties. Change the style, scale, fonts, columns etc. will it works with your output. 60

61 Adding grids, scale and north arrow To add a coordinate system to your output, right click the main data frame. Click properties. Click on Grids tab. Click new Grid. Choice either graticules for lats and longs or measured grid for UTM units. Choice if you want grid lines, ticks or blank and the interval. You will then have a correctly scaled grid for your image. The same can be done for a secondary data frame. Add a scale bar from the same insert menu. Click properties. Remove the division before 0 and if in the UK or Australia and using Kilometres, edit the label box to spell this correctly. Number of divisions depends on how detailed you need the scale. You can add a north arrow using the same menu and its pretty straight forward. Resize by dragging the blue corner nodes once on the layout page. 61

62 Secondary data frame Either drag items down into the new frame or add them as you would for the primary frame. If you want to show the extent of one frame on other. Select the frame you want to show it on. Click on extent Indicators tab Click the arrow to move the data frame to the right hand column for it to show in extent. Click Frame to choose the thickness of the outline etc. This extent will change as you move in or out and will always represent a geographically correct extent. 62

63 Exporting many options 63

64 Post GIS image processing You can edit your images in Adobe illustrator fro ArcMap by saving as an.ai. Remember to click update on opening the file in adobe for fonts as these vary and will not show otherwise. Use the direct select tool (white arrow) to select text or symbols. You also have layer control on your vector data layers. Releasing clipping masks will allow editing of complex line work. 64

65 Interoperability options Toolbox for KML, raster conversions in and out Plugins e.g. ogr2gui_0.6 for mapinfo/arcgis conversions. Hawks Analysis Tools ETGoowizards AI (Adobe Illustrator) output. Remember to use the direct select (white cursor arrow) and release clipping masks to edit the data in AI. 65

66 ArcToolbox Conversion tools Raster to shapefile conversion Creating Feature classes Defining projections reprojecting Spatial analysis tool for extracting data Interpolation Fields assigning auto text/# to fields Analysis tool Extract (clip) 66

67 Geoprocessing 67

68 Other tricks 2 linked layers for insert maps with correct scale box Clipped data from a shape e.g. coastlines for good images Masking data permanently or just colour mask e.g. remove background Use of the pause and refresh buttons Cross section construction plugin Elevation and other geophysical data available at: GADD at GA 68