Geography 121 Project 3 Presentation National Map Data by Ron, Lauren, and Hannah

Objective for Project 3 Ability to find, download, and view National Map Data of your hometown or area of interest.

Introduction This project will be evaluating the use of aerial photography and elevation data in the creation of maps. Many developed countries’ government programs have developed large sets of topographic maps to help build roads and cities. The U.S. Geological Survey (USGS) is responsible for topographic mapping in the U.S..U.S. Geological Survey (USGS) We have already learned in class, that a vertical aerial photograph is an image taken from above the Earth's surface. Elevation data on the other hand is used to calculate slope. (Previous lectures) Raster elevation data tends to be best.

Three types of National Map Data (DEM) Digital Elevation Model (DLG) Digital Line Graphs (DOQQ) Digital Orthophoto Quarter Quadrangle

How to get started!! First few steps: Go to my computer Find your WWW drive Make a folder, “Map Data” for the project Make 3 separate folders for each type of map; called DEM, DLG and DOQQ You need these to hold the downloaded data for each map

What are DEM’s? Digital maps showing land elevation of Earth areas Most maps made through use of aerial photographs Used the most due to simplicity Good for showing land features A DEM is a raster illustration of a terrain surface. Raster: FROM OCT. 18 LECTURE - Data broken down into grid cells - One cell has one attribute, groups of cells form objects

What a DEM looks like

Uses of a DEM Depicts the Earth’s elevation of a place of interest or in this case, your hometown Shows physical features of a chosen place or position: Rivers, lakes, mountains, etc.

Creating your own DEM Enter the website: On the right you will see,“View and Download United States data.” Click on it! Take your mouse and draw a square around the chosen area NED Relief (1 arc second) must be checked under the elevation tab Use the “define downloads area” on the left hand side. YOU MUST CLICK ON IT! Target the area, and then click download

Creating continued…. Hold your horses! The download takes some time Open the file. Click “use evaluation version” Highlight all the files and click “extract” Extract the files to the DEM folder you made previously, then OK Find and open the ArcMap program Go to Add Data and find the map you are using The computer might ask something about pyramids, just click Yes to all pop-ups, the map should appear Save this file to your WWW!

Uploading DEM image When your map is uploaded, hold down alt and print screen so you will take a screen shot of the program to put on your website Now go to Start, Accessories, and then Paint Go to Edit and click on Paste, your image should appear Save this image in your WWW folder. You can now use this image for your project. REPEAT THESE STEPS FOR ALL 3 MAPS!!

Further DEM help Sources dem.htmlhttp://rmmcweb.cr.usgs.gov/elevation/dpi_ dem.html %20Home.html - UNDER PROJECT 3http:// %20Home.html m.htmlhttp://edc.usgs.gov/products/elevation/de m.html

DLG Scales Digital vector representations of cartographic information Made of nodes or points, line segments connect to these nodes, and these areas are formed by 3 or more line segments

DLG Scales continued Large Scale (7.5 minutes): 1:20,000, 1:24,000, and 1:25,000. Intermediate Scale (60 minutes): 1:100,000 Small Scale: 1:2,000,000 and are split by State or split into sections

What DLG Scales Show Boundaries- (ex: Political) Hydrography- (ex: Lakes, Rivers, Streams) Hypsography- (ex: Contour lines, 50 Meter Contour Interval) Public Lands- (ex: Section Lines) Transportation- (ex: Miscellaneous Features, Roads, Railroads)

How to create a DLG 1 st : nload.cfm nload.cfm 2 nd : Chose your state 3 rd Chose your County & 3 or more Variables (Physical, Rails, Roads, Landmarks etc..) After Choosing Select “Download File” –(Use Evaluation Version) (Continued Next Page)

DLG Cont. 4 th : Create New Folder 5 th : Highlight all files and Extract them into New Folder 6 th : Open Arc Map 7 th : Select “Add Data” 8 th : Go to New Folder and Highlight all Data

DLG Image

Another example of DLG image

DLG Helpful Sources pol.htmhttp:// pol.htm so_rev1.htmlhttp:// so_rev1.html

What is a DOQQ? Computer Generated Image Aerial Photograph Image Displacement Caused By Terrain Relief And Camera Tilts Is Removed Possible to Measure Directly On It Created by scanning aerial photograph transparency and digitally rectifying the image to an orthographic projection (orthorectification)

Uses of DOQQ They are mostly used in editing vector planimetric data. –Road data can be taken by the state and plotted over DOQQs so that they can then be changed to show the new road layout. This was found in the Online Text, Module 3, Part 2

DOQQ Image

Creating A DOQQ 1.Use Like the DEM, zoom into your area 3.In the Orthoimagery tab, select 3.In the Orthoimagery tab, select “DOQQ Color Mosaicked Image.” 4.Using the Define Download Area button highlight the area you want to download 1.Make the area small

Continued Creating a DOQQ 5. Proceed with the same download, extract and loading into ArcMap as the previous two maps 1.Warning: DOQQ Files are huge! 2.Delete them after you use them!

Finally….lets wrap things up! DEM: Relating back to previously learned material -In Module 4, Part 3; “DEM's are cast on the Transverse Mercator projection used in the local UTM zone.” The USGS 7.5-minute topographic quadrangle set is the most detailed data. DON’T FORGET: No map is completely accurate, including DEM's!

DLG Conclusion DLG Provides Useful Data –Many Perspectives –Good for evaluating an area –Planning –Finding Problems and Solutions

DOQQ Conclusion Due to the scale of the map, 90% of well-defined points are 20 feet of their actual positions. However, error arises during the rectification process, when the image is warped in order to have 16 points match their actual location The main part of the DOQQ is the pixels. Each pixel represents a number, 0 for black, 255 for white, and levels of gray in between. This information was taken from the Online Text, Module 3, Section 2

Project Page Directions Refer to u.edu/courses/geo g121/projects/proj3 _example.html u.edu/courses/geo g121/projects/proj3 _example.html

SOURCES For DEM and DOQQ Maps- For DLG- m m Definitions and uses of maps: Understanding Geographic Data Online Text: m?c=31&CFID=133657&CFTOKEN= &jsessio nid=a23063e377ce3f4512d7 Helpful website:

Need our help? Just ask.. Lauren Rosenman: – Hannah Ryan: – Ron Feingold: –