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Maputo Map Creation Procedures 3 Oct 2012, Emily Eros 1. Base imagery and roads Sourcing from ESRI World Imagery base layer 1 Also sourcing OpenStreetMaps 2 as a (partially-transparent) overlay Checked projection of the map – our base layers are projected in WGS 1984 Web Mercator, with units in metres. I’m okay with that – WGS 1984 is the spheroid we want to use, and the Mercator projection is good for north-south-oriented regions and areas like Mozambique. I’m not sure about the “web mercator” part, but I know Web Mercator is required for some forms of online, interactive maps, so let’s go with this. I’ll be working with backup data on my USB key and we may move 1 This map presents low-resolution imagery for the world and high-resolution imagery for the United States and other areas around the world. The map includes NASA Blue Marble: Next Generation 500m resolution imagery at small scales (above 1:1,000,000), i-cubed 15m eSAT imagery at medium-to-large scales (down to 1:70,000) for the world, and USGS 15m Landsat imagery for Antarctica. The map features i-cubed Nationwide Prime 1m or better resolution imagery for the contiguous United States, Getmapping 1m resolution imagery for Great Britain, AeroGRID 1m to 2m resolution imagery for several countries in Europe, IGN 1m resolution imagery for Spain, IGP 1m resolution imagery for Portugal, and GeoEye IKONOS 1m resolution imagery for Hawaii, parts of Alaska, and several hundred metropolitan areas around the world. Additionally, imagery contributed by the GIS User Community has been added in Alaska, New York and Virginia. i-cubed Nationwide Prime is a seamless, color mosaic of various commercial and government imagery sources, including Aerials Express 0.3 to 0.6m resolution imagery for metropolitan areas and the best available United States Department of Agriculture (USDA) National Agriculture Imagery Program (NAIP) imagery and enhanced versions of United States Geological Survey (USGS) Digital Ortho Quarter Quad (DOQQ) imagery for other areas. For more information on this map, visit us online at http://goto.arcgisonline.com/maps/World_Imagery 2 http://www.OpenStreetMap.org.

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Maputo Map Creation Procedures 3 Oct 2012, Emily Eros

1. Base imagery and roadsSourcing from ESRI World Imagery base layer1

Also sourcing OpenStreetMaps2 as a (partially-transparent) overlay

Checked projection of the map – our base layers are projected in WGS 1984 Web Mercator, with units in metres. I’m okay with that – WGS 1984 is the spheroid we want to use, and the Mercator projection is good for north-south-oriented regions and areas like Mozambique. I’m not sure about the “web mercator” part, but I know Web Mercator is required for some forms of online, interactive maps, so let’s go with this.

I’ll be working with backup data on my USB key and we may move the data in the future, so I’m going to use relative pathnames to make it easier to restore/load the map after moving data.File Map Document Properties Store Relative Pathnames (checked)

2. Add Mozambique data just for fun since this is a basemap and I want to see what’s out there.Sourced from GeoCommunity (http://data.geocomm.com/catalog/MZ/index.html). You need an account to use this website, though most data is free.

I downloaded a bunch of roads, utilities, and other transit data. They came as zip files which unzipped to a .e00 extensions. This extension is for an ArcInfo interchange file. There are some particular rules for using this data; you have to have the right sort of filename and stuff. Also, WinZip can mess with the data. If you’re ever having problems, here’s a link to file specs, WinZip troubleshooting, and the instructions for importing interchange files (scroll down to ArcGIS 10 instructions): http://support.esri.com/es/knowledgebase/techarticles/detail/21052

1 This map presents low-resolution imagery for the world and high-resolution imagery for the United States and other areas around the world. The map includes NASA Blue Marble: Next Generation 500m resolution imagery at small scales (above 1:1,000,000), i-cubed 15m eSAT imagery at medium-to-large scales (down to 1:70,000) for the world, and USGS 15m Landsat imagery for Antarctica. The map features i-cubed Nationwide Prime 1m or better resolution imagery for the contiguous United States, Getmapping 1m resolution imagery for Great Britain, AeroGRID 1m to 2m resolution imagery for several countries in Europe, IGN 1m resolution imagery for Spain, IGP 1m resolution imagery for Portugal, and GeoEye IKONOS 1m resolution imagery for Hawaii, parts of Alaska, and several hundred metropolitan areas around the world. Additionally, imagery contributed by the GIS User Community has been added in Alaska, New York and Virginia.

i-cubed Nationwide Prime is a seamless, color mosaic of various commercial and government imagery sources, including Aerials Express 0.3 to 0.6m resolution imagery for metropolitan areas and the best available United States Department of Agriculture (USDA) National Agriculture Imagery Program (NAIP) imagery and enhanced versions of United States Geological Survey (USGS) Digital Ortho Quarter Quad (DOQQ) imagery for other areas.

For more information on this map, visit us online at http://goto.arcgisonline.com/maps/World_Imagery

2 http://www.OpenStreetMap.org.

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Note: When converting several files at the time, you can right-click “Import from E00” in the ArcToolbox menu and select “Batch”. That processes multiple files at once.

I checked the layers and didn’t like what I saw – Geocomm roads didn’t line up with OpenStreetMaps (which seems more reputable in this case – it’s more locally-created and it lines up better with topography and aerial imagery). It’s not a projection issue but a data-quality issue. When I try to investigate the attribute tables, ArcMap crashes. Seems suspect.

I’m removing and deleting the Geocomm data.

3. Downloaded elevation data for the relevant area of Mozambique (10 degree grid: 20-30S, 30-40E) from the Geocomm site3. The DTED (Digital Terrain Elevation Data, Level 0) data comes in several grids. We need the grids for e032: s26 and s27. The rest are for other areas of Mozambique and can be deleted to conserve file space.

I’ve grouped and renamed the DEM layers to make them easier to work with. For the display, each DEM grid has its own scale of colours from low to high. I’m going to standardize these between grids. In the “Properties” menu for the DEMs, I’ve set a scale from 0 to 1000. 0 to 1000 of what units? There’s no metadata to answer that, but googling tells me that DTED data always supplies elevation data in metres.

I overlayed the DEM data on the imagery and did a partial transparency to make sure the elevation data lined up with the land and sea, and to ensure that the two grids lined up seamlessly. Looks good.

3 Source info: http://data.geocomm.com/readme/dted/dted.html

In support of military applications, the National Imagery and Mapping Agency (NIMA) has developed a standard digital dataset (Digital Terrain Elevation Data (DTED®) Level 0) which may be of value to scientific, technical, and other communities. This DTED® product is a uniform matrix of terrain elevation values which provides basic quantitative data for systems and applications that require terrain elevation, slope, and/or surface roughness information. DTED® Level 0 elevation post spacing is 30 arc second (nominally one kilometer). In addition to this discrete elevation file, a separate binary file provides the minimum, maximum, and mean elevation values computed in 30 arc second square areas (organized by one degree cell). Finally, DTED® Level 0 contains the NIMA Digital Mean Elevation Data (DMED) providing minimum, maximum, and mean elevation values and standard deviation for each 15 minute by 15 minute area in a one degree cell. This initial prototype release is a "thinned" data file extracted from the NIMA DTED® Level 1 holdings where available and from the elevation layer of NIMA VMAP Level 0 to complete near world wide coverage.The current DTED® Level 0 and subsequent releases will be updated consistent with established NIMA production maintenace procedures.

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4. Dowloaded 1M drainage area for Mozambique (rivers). If this is wrong, we could model it ourselves using hydrology application of ArcMap. I extracted the zipped files, imported from e00 to coverage (see ESRI instructional link above) and added the files to the map. Lines up but crashes ArcMap every time I try to check the attribute table. That’s no good. I’m done with GeoComm sourced from ESRI.

5. Let’s try geocoding our participatory mapping points. First I’m going to clean up the database. We need all classifications to be numeric, so I added a land use code. I also split the coordinates into an X and a Y column. I saved the excel file, closed it, added it to the map, and checked the attribute table to make sure everything looked okay.

I’m a little nervous about geocoding WGS coordinates, but here goes. First, I changed the coordinate system of the data frame to the same as the incoming XY layer’s projection (GCS WGS 1984 – you select this by right-clicking “Layers” and changing the projection).

The “Add XY Data” option is hidden away in ArcMap 10 – you have to go to File Add Data Add XY data. In the menu that appears, my data isn’t showing up properly – only a few columns show up. Weird. I checked out some troubleshooting strategies on ESRI’s website4. Seems like the problem is because I have coordinates in degrees-minutes-seconds and I want them in decimal degrees. I’m going to convert them. I do this by running the Convert Coordinate Notation geoprocessing tool (Find it under ArcToolbox Data Management Projections and Transformations) and then performing a join to preserve other fields5. This failed. I think this is partly because I needed to use a positive/negative denotation rather than “E” and “S”. When working with coordinate systems, we generally use the following system to denote direction: • Northern: +Y • Southern: -Y • Western: -X • Eastern: +XChanging this didn’t help. ESRI tells me it’s because degree-minute-second (DMS) coordinates are single string and must be in the format DD MM SS.ssss DDD MM SS.ssss. Latitude is first followed by longitude separated by spaces. I changed this in the input file and tried again. No luck. At this point I just did the conversion manually in Excel by splitting the degrees/mins/secs into different columns and then adding them together (Decimal degrees = (Seconds/3600) + (Minutes/60) + Degrees). I copied and pasted as values to make this GIS-compatible.

Back to the beginning – we’re going to re-try adding the coordinates as XY Data. Success!

4 http://support.esri.com/en/knowledgebase/techarticles/detail/399725 For more info on manipulating coordinates: http://blogs.esri.com/esri/arcgis/2011/01/05/converting-and-displaying-coordinates-in-arcgis-10/

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A few points are in suspicious locations – looks like a typo in a few coordinates. Another coordinate is in a marsh. We checked the typos for this, fixed the Excel sheet, and re-imported the coordinates.

Success! The points are all showing up on the map in spots that make sense.

6. Bring in the AutoCAD files, which have been uploaded to DropBox. Normally bringing AutoCAD files in involves lots of geocoding and headachey stuff, but it looks like these have already been given spatial references and a projection, and have already been converted to GIS-compatible shapefiles. GREAT. I added all the polygons and polylines into ArcGIS just by clicking the “Add Data” button.

The shapefiles appear in the Table of Contents. It looks like a bit of a mess and needs to be cleaned up. When converting from AutoCAD to GIS, each layer is broken into two layers – one for enclosed objects (polygons) and one for not-enclosed objects (lines). I grouped together the polygon and polyline file for each layer and named them with meaningful names (water, transportation, structure, property lines, and contour lines). For the water and transportation and contour layers, we can turn off and ignore the polygon file – the shapes aren’t meaningful, they just occur because rivers or roads intersect. For property lines, everything should look like a line since property boundaries are, by definition, lines. So, for this layer, I’m going to set the polygon fill to null and the line to match the colour of the polyline shapefile. For the structures layer, everything should be a polygon since buildings are solid objects. Let’s try closing these off.

To close off the building lines, we convert them to polygons. Select ArcToolbox Data Management Tools Features Feature to Polygon. This worked (the second time around) but it produced a layer identical to the existing polygon file and didn’t convert all the lines to shapes. We’re going to try again with increased XY tolerance (this means that ArcGIS will close a shape whose endpoints have a bigger gap between them). I measured a sample building gap (of >1m) and decided to set the XY tolerance to 2 metres this time. It looks terrible (see below):

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I think this is happening because the XY tolerance is big enough that ArcGIS can skip between points, so I tried one more time with XY tolerance of 1m. Results are better but not perfect. Trying with 0.8 metres. That still makes incorrect shapes. Instead, I’m going to figure out how many polylines (5104) are not also polygons (5007). 100 is a realistic number for me to edit by hand. It would take an hour or two to do this by hand, provided I am able to isolate the un-closed lines. Let’s leave this for later and deal with more pressing stuff since the buildings don’t match up exactly, anyway.

7. Topo lines. I checked the AutoCAD contours (these type of lines export notoriously badly, in my experience). There’s no elevation value for the lines and I found a few other problems. That renders this shapefile basically useless. I can generate these with the DEM downloaded earlier. First, enable the Spatial Analyst extension (which does a lot of environmental-type GIS). Enable it by going to Customize Extensions and checking the appropriate box. Next, go to ArcToolbox Spatial Analyst Tools Surface Contour and drop in the first DEM. I tried 100m contours first and got an error (I think ArcMap doesn’t like nested layers, or it was unhappy that I wanted to save as an independent shapefile and not in the geodatabase). Moved layers around in the Table of Contents and tried again, but with 50m data. Success. Got a weird line at 0m, but I can delete that later.

I ran the contour tool again with 10m contours to see what they’d look like. The error earlier must have been from not saving to a geodatabase. Here’s a snapshot of the resulting layer:

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I repeated the process with the second DEM and then exported both shapefiles from the geodatabase to a spot on the server where I could find them. I also deleted the 0m contour because it just messes up the sea level line. To do this, turn the editor on, open up the attribute table for the relevant file, sort by the “contour” column, and highlight the records with an elevation of 0. Right-click and delete these records, then save your edits and turn the editor off.

I could join these contours into one file but I don’t really see a reason to at this point. Also, there’s a ~450m gap between the two sets of contours. This isn’t something of concern for most uses of DEMs. Most programs/tools that would perform analysis can interpolate between lines.

I also tried 1m contours to get more precise elevation data. My contours don’t match (or look as good as) the elevation-less contours from the AutoCAD files.

8. Classification of points. I changed these under “Layer Properties”. I’m going to do this first in English and then in Portuguese. I’m going to save a separate .lyr file for each, which will save the classification and display information.

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9. I didn’t like the logos, so I downloaded some from the internet. I used this website (http://mapicons.nicolasmollet.com/) and modified the colors. I used these in Google Maps, Ushahidi, and ArcMap.

10. I converted the shapefile of Maputo points into a KML (make sure the projection is Web Mercator first so that the projection comes through okay) and loaded that into a new map on Google (go to “My Maps” and create a new one). Laura uploaded all our icons as individual pages on Gabriella’s website and I individually went through and changed each point to the correct icon. Ugh. The map is editable only by me, Gabriella, and Laura.

11. I set up an instance of Ushahidi for the points to make it easy for field assistants to add points into a map this summer.