LAB 5. Assigning Coordinates to Images Raster images in several formats, including JPEG and TIFF, can be georeferenced to coordinate systems if certain parameters are known. This allows co-registration of the images to vector data. For this lab, there will be two maps, Lab5a and Lab5b. Lab 5a The easiest method is to use the Georeferencing tool If the tool is not visible, please activate it by going to the “Tools” pull-down menu and look under both “Customize” and “Extensions” to check the activation boxes. Step 1. Use ArcGIS to open Basemap.jpg (download it first - use save target as using the right mouse button).  Make sure its extension is .jpg, not.jpeg. DO NOT BUILD PYRAMIDS. Step 2. Click on “Georeference” and unselect “Auto Adjust” Step 3. Add ground control points at the center of the tic marks on the map using the tool that looks like two Xs connected by a diagonal line. Click on this tool and then left-click once on a tic mark. Then move you cursor off of the tic (you will notice a line it creates) and then right-click and choose “Input X and Y”. You can then type the coordinates in the pop-up box. Step 4. After you have three ground control points completed you need to go back to “Georeference” and select “Auto Adjust”. The map will now likely disappear. To get it back, click the “Full Extent” button. Step 5. Go back to “Georeferenceing” and choose rectify and follow the instructions. Step 6. Close your current map document and open a new one. You now need to find the rectifed file using ArcCatalog. Right-click on the image name and choose “Properties”. Now scroll down to “Spatial Reference” and define the projection as Utah State Plane, North Zone, NAD 27. Check your map accuracy by putting the cursor on each of the tic marks and comparing the coordinates given by ArcGIS to those written on the map. <>Finally, make a layout using your raster map, place a state plane grid (find in Data Frame Properties) around it and include a title, north arrow, and scale bar, and mention the spatial accuracy. Also, put a second neat line around the entire map and ancillary graphics using the graphics rectangle tool. Lab 5b For the second part of Lab 5download this data and unzip it. This creates a new folder called Georef containing your data. Open two ArcGIS sessions add the geol_tr.img to one session and the sections Shapefile to the other. DO NOT BUILD PYRAMIDS!!! You will find the coordinates of section corners and use those to rectify the image. Use Select by Attribute (Selection pull-down menu) queries to find sections of interest. Start with this query: "TNUM" = 30 AND "RNUM" = 12 AND "SECTION" = 10 Zoom in on this section and click on the lower-right (southeast) corner with the Identify Tool. The UTM coordinates will appear next to the Location annotation in the pop-up window. You can cut and paste these, but make sure to remove any commas. Next click on Georeferencing (if this tool is not present open the Tools pull-down menu, click on Extensions and make sure it is checked and then click on customize (Tools once again) and check Georeferencing) and uncheck Auto Adjust. Then find the southeast corner of the correlative section on the geologic map image and left-click on it with the Add Control Points tool. Then move the tool slightly off of the point and right-click to open the input box for the coordinate. Either type or paste the coordinate in. Repeat this process for four control points and then check Auto Adjust. You will then need to click the Full Extent button to see your map again. Open the ground control table and check your RMS error. If it is high check for errors. You can then go back to the Georeferencing pull-down menu and select Rectify. Save your rectified image and then open ArcCatalog. Right click on the rectified image and select Properties. Then scroll down to Spatial Reference and edit for UTM Zone 12, NAD 83. You will need to open a new Map Document and add the rectified data. If you add the rectified data to the same Map Document you did the georeferencing in, it will not show the proper coordinates. Make a new map with the rectified image overlain with the sections Shapefile. Make a map in Layout View and turn it in. Below are instructions for making a World file – this is not part of the assignment, just old information that may come in handy sometime. Goals: 1. Determine the pixel (grid cell) size both in X and Y. 2. Determine the XY coordinate of the upper-left image (raster) pixel. 3. Build a World file -a text file with coordinate and pixel size information. 4. Use ArcCatalog to generate spatial reference Proceed as with this assignment as follows: Note: the map coordinates are State Plane, Utah North. Step 1. Use ArcView to open Basemap.jpg (download it first, of course - use save target as using the right mouse button)  Make sure its extension is .jpg, not .jpeg. Step 2. Open the above file in Arcmap. Raster image coordinates are determined from the upper-left hand corner pixel. Note that a tick mark with a state plane easting and northing is near the upper-left corner. There are also tics in the upper-right and lower-left corners. Step 3. Determine pixel size. Take the screen coordinates of the upper-left, upper-right, and lower-left tic marks. Do this by placing the cursor at the center of each and reading the coordinate at the bottom-right of your ArcView window. Then subtract the upper-left X screen value from the upper-right screen X value to determine the total number of pixels between the tic marks. Now subtract the upper-left map X coordinate (state plane feet) from the upper-right X coordinate. Divide this value by the total number of pixels you derived previously to get the pixel size, in feet, along the X axis. Now repeat this process for the Y direction (Upper-left & lower-left tics). Step 4 - Determine the map coordinates for the extreme upper-left image pixel (not the tic!). The logic here is similar to that for finding the pixel size. You determine the number of pixels from the upper-left tic to the top and left image margins. For the X coordinate, multiply the number of pixels between the tic and the left margin by the X axis pixel size in feet, and then subtract this value from the X map coordinate of the upper-left tic (easting values are decreasing to the west) Now repeat this process for the Y coordinate. Determine the number of pixels between the upper-left tic and the top image margin. Multiply this by the Y axis pixel size in feet. Now add this value to the Y map coordinate value (values are increasing to the north). These XY coordinates are used for the upper-left image pixel. Step 5. Make a world file. Now a text file, called a world file, must be created. You can do this with any text editor such as Notepad or Wordpad. The extension of the text file must end in the first and last letters of the image type file extension and end in a w. For instance, a world file named test, for a JPEG (.jpg) file, would have a .jgw extension: test.jgw. To build this file we use the following information: 1. Spatial resolution (pixel size) for X 2. A rotation term (zero for this) 3. A rotation term (zero for this) 4. Spatial resolution (pixel size) for Y (must be negative) 5. The upper-left X coordinate in state plane 6. the upper-left Y coordinate in state plane The completed file will look something like this (note: these are example coordinates and will not work for your assignment and the notes I have included are not added to the file): 5.00000000 (note: 5 meters, 5 feet, 5 kilometers, etc) 0.00000000 (note: rarely used, usually zero) 0.00000000 (note: rarely used, usually zero) -5.01200000 (note: 5 meters, 5 feet, 5 kilometers, etc) 14569093.00000000 (note: map coordinate, i.e. UTM) 342900.00000000 (note: map coordinate, i.e. UTM) For "basemap.jpg" the world file would be named "basemap.jgw" Add the world file to the same folder as the JPEG image.  Open a new blank document in ArcMap ("File" pull-down menu) and reload the basemap.jpg as a new layer. This will allow ArcView to read the world file. Now go to Data Frame Properties (under the View pull-down menu). Click on the Coordinate Systems tab. Use the "Predefined" folder to find State Plane NAD 27. Then choose Utah North. If you look into the folder containing the image, you will notice that ArcGIS added a .aux file containing the coordinate and datum information. To check your accuracy, place the cursor on each of the tics and record their values.