Introduction to Projections week 5

A map projection is the result of transforming 3 dimensional earth to a 2 dimensional map. Different projections have different distortions.  This could be partially due to the developable surface (plane, cylinder or cone). The developable surface could be tangent (touching) or scant (intersecting).  The farther from the tangent or scant the data the greater the distortion.  Map projections can have some but not all: true directions, true distances, true areas, true shape.  Consistent projections are important in datasets to ensure accurate analysis (don’t want to be comparing apples and oranges).

This weeks map and included table highlight four Florida Counties to be compared in three projections.

 Albers, a dual line conic projection, is said to accurately represent area.  UTM, Universal Trans Mercator, is a cylindrical projection from a meridian (N/S), area and shape are distorted as distance from the meridian increases.  State Plan is not a projection but a coordinate system that then uses a projection, in this exercise it is Lambert Conformal Conic, that strength lies more in shape than area.  In the comparison of the exercise UTM 16 N shows the greatest distortion in Miami-Dade county and almost no distortion in Escambia county.  Escambia county is nearly centered horizontally within the projection area of 16.  Miami-Dade is in UTM 17 – farther away from area 16 and therefore more distortion.

This week (4) the focus was on sharing maps.  I explored internal data (data provided in the lab) and external data (ArcGIS online-world street maps). I created a list of the top 10 Alabama State Parks for cottages.  The list was initially rendered as an Excel table.  Then saved as a text document.  The text document was loaded into ArcGIS.com to covert to a point shapefile (geocoding). More button pushing and "BAM! My first web map." Click on the link:  Alabama State Park Cottages  I had some difficulty exporting the online map as a map package for use in ArcGIS, but did finally accomplish.  Here is a look at the map.

The final map for this week required creating a KMZ file (Utilized "Layer to KML Conversion" tool) from my Top 10 layer (shown above on the basemap). Here is a picture of my KMZ file layered with google earth!

Works better in google earth where you can zoom and click on the park symbol to get the name of the park, address, and a URL to the website.  

This week I created 3 maps, but I did each of them several times.  I have chosen to include two versions of the second map here as a reminder that sometimes starting over due to technical issues ( couldn't access my data after completing the map and saving a jpeg, message says it was created with an earlier version, and second time realizing I was half in one drive and half in another).  The blue background was the initial map.  I still don't know why or how I got it to have a blue background, or why the second one doesn't.  I think sometimes you just have to go with it.  As I worked through the lab for the second time I realized that I was getting faster.  I accessed the ArcCatalog as a stand alone feature and as a window within ArcMap.  Reviewed the views of the table of contents:1) List by Drawing being the most comfortable for me, probably since this is the view I have been using so far. 2) List by Source was interesting to see where my data was coming from 3)List by visibility helped to answer summary question (count of selected features) 4)List by Selection not sure how to utilize this yet.  Used select by attribute to build a SQL queering to create a new shapefile. I practiced labeling features both all of the labels for a layer and later limited the labels by population.  Updated Map Document Properties under the file tab, to utilize dynamic text for author and date.  Recognized I don't like messy maps, maps with too many fields.  The one that I have included has rivers, roads, railways and some cities.  It was very difficult to try to find a place for the labels for the cities in all the roads and rivers.  Changing the labels to attributes and saving to the map allowed me to move them around but even then I could only look for the least interruptions as the rivers and road are everywhere.  Worked with raster data for the first time.  It looks different from the vector data we have been using.  It seems to come as a whole unit.  Vector data has attributes that can be limited, labeled, and symbolized.  Raster doesn't appear to be as malleable.  Classified symbology of the raster data provided clear lines of distinction to the data.  The stretch symbology gave a more natural feel of fading from one level to the next.  Challenging week, but the challenge provided the opportunity to do the maps again and again.  Learning more and becoming more comfortable each time.

Week 2: Own your map

Lab module 2 went a little smoother, less technical issues.  Was able to follow the lab instructions (pretty well). Working with multiple data frames was not as confusing as I anticipated.  I really like the zoom to layer for when I get the layout all kinds of off kilter.  Zoom to worked well on the Florida map putting it right back in the center of the data frame.  Zoom to did not work so well for the Escambia county map.  The map was much too small until the data was clipped to Escambia county and even after that it was just not where I wanted it or the right size.  I did make some progress in looking at metadata.  Publication information and time period is found in the Identification section. Projection and Reference are found in the Spatial Reference section.  Defiantly not an expert, but progress. Clipping data worked exactly as the lab instructions indicated, probably need to do that a few more times.  "Symbology" table was helpful in making decisions (and not getting too creative). Can't forget the Essential Map Elements: title, legend, scale, north arrow, creators name and the date it was created and don't forget the data source information.

Lab module 1 process was daunting and at times frustrating for this first timer.  Data had to be extracted from the R: drive to my S: drive.  4043 GIS Intro folder.  Module 1 folder.  Except the first go at this I misspelled Module as "moduel".  When I corrected the spelling then I lost my data.  So back to extract again.  The outline in the overview provided for this lab worked very well.  It was slow going for me as this is all so new.  Map document (.mxd) does not contain data.  To move or share MXD file the data files must go as well.  To share the map export it to jpeg (hoping this eliminates the need for data files).  I explored the toolbar: zoom in and out, taking notice of the scale display changes 1:1000 being bigger than 1:1000000, similar to fractions 1/1000 is bigger than 1/10000000).  I panned all around while zoomed in and lost myself, but was able to center by right clicking World Countries layer and selecting zoom to layer.  I looked at metadata in the .xml file.  Looking was all I am able to attest to, didn't understand most of it (another opportunity to learn latter). I sorted an attribute table by a field (column) and was able to locate items on my map by locating the record (row) right clicking the farthest left cell and clicking zoom to. I selected islands on the map utilizing the select features tool and obtained information about the islands by show selected records button.  I identified parts of my map by utilizing the identify tool. I located areas of my map by using the find tool and then right click the result I need to pan to the location.  I used the xy tool to locate on my map and used the measuring tool.  Although since the polygon to be measured was irregular shaped I am not sure how there would be a correct answer for a measurement (there would be different answers based on the location of the measurement). 

The map itself:  The world Countries with a layer for cities.  I changed the symbol for the cities. The color of the countries is graduated by population.  Changed the view from data view to layout view and utilized the layout toolbar.  The layout toolbar for use in layout view (the data extent does not change) and the tools toolbar is used for navigating the map view.  Changing the data frame from portrait to landscape by select and drag the top right corner of the data frame posed some clumsy ineffective attempts for me.  I was able to right click inside the data frame, click distribute and fit to margins to get it (much easier). I added essential map elements: North arrow, scale bar, title, legend, data source, my name (and later the date of creation).  Finally exporting the map as a jpeg. and saving it.

Using ArcGIS Help in my browser was a no go for me.  I could pull the web site, and would search, being sure it was for my version 10.5.1, and the result was no results available try again later.  So I improvised and used wiki.gis.com and then moved on to the ArcGIS desktop help.

Overall this was a ton of new information.  Hopefully I will have less technical issues and be able to move a little quicker next time.