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GIS Help Clinic

  • #1
    Registered Users Posts: 3,483 Ostrom


    I'm not a geographer, my field is in economics. However, I am currently working on something which leans heavily on historical economics, and geography. In fact, it was my search for geography people that led me to request this forum! I was having issues with trying to create maps using the Koppen-Geiger Climate Classification system. In fact, if anyone knows how to use GIS, I reckon opening a help/clinic thread for this program might be a good idea!

    Are you using arcview? Sounds good (help thread)! I had similar difficulties using Laslett's classification of family types on irish census data.


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Comments



  • I think so, to be honest I never used this stuff in my life but the data I got came in a few formats so I tried it out on what I think was arcview.

    Tell ya what, I will start a GIS thread.




  • Ok, so people can post here for help using GIS/Arcview, or post any useful online guides they know of, etc.




  • Will post as soon as i'm not depending on my phone! Can we link to files?




  • So, step one down :D What exactly are you trying to do?




  • Ok, so I have been using the Köppen climate classification system, with particular focus on the Americas. I would like to be able to break the data down by country (or state) for a more granular analysis, or just for prettier maps for my project. I know what I am looking to take out of this data, but I'm not sure what I can get out of it, other than what I have been doing so far, which is taking the central co-ordinate for each state and using the classification for that (rough, I know) They have provided the data, so what can I do with it? Take Argentina as an example.

    Source:

    http://koeppen-geiger.vu-wien.ac.at/

    More directly:

    http://koeppen-geiger.vu-wien.ac.at/shifts.htm#data

    Wikipedia explanation:

    http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification


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  • Ok, so I have been using the Köppen climate classification system, with particular focus on the Americas. I would like to be able to break the data down by country (or state) for a more granular analysis, or just for prettier maps for my project. I know what I am looking to take out of this data, but I'm not sure what I can get out of it, other than what I have been doing so far, which is taking the central co-ordinate for each state and using the classification for that (rough, I know) They have provided the data, so what can I do with it? Take Argentina as an example.

    Source:

    http://koeppen-geiger.vu-wien.ac.at/

    More directly:

    http://koeppen-geiger.vu-wien.ac.at/shifts.htm#data

    Wikipedia explanation:

    http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification

    Save the zip files to wherever you're saving your data (e.g. your c drive), unzip and save it under a new name, open arc view, and arc catalogue and go to the unzipped file and it should be there. It's been a while since I've used arc but that's what I can remember.




  • Ok, so I have been using the Köppen climate classification system, with particular focus on the Americas. I would like to be able to break the data down by country (or state) for a more granular analysis, or just for prettier maps for my project. I know what I am looking to take out of this data, but I'm not sure what I can get out of it, other than what I have been doing so far, which is taking the central co-ordinate for each state and using the classification for that (rough, I know) They have provided the data, so what can I do with it? Take Argentina as an example.

    Source:

    http://koeppen-geiger.vu-wien.ac.at/

    More directly:

    http://koeppen-geiger.vu-wien.ac.at/shifts.htm#data

    Wikipedia explanation:

    http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification

    I think this is what your are trying to do? Not sure, let me know
    108182.JPG




  • Yeah, but there is such a map provided by the website. Is there a way of focusing on one country, to flesh out the different climates within this country? Can the data for one country only be cut out of the dataset?




  • Yeah, thats possible. The climate data on the above map is in a gridcode. Ive never worked with them before so it would take me a bit to figure it out and i dont got the time today.

    .....but with GIS theres always a way:p

    Actually Cork Girl might know more about gridcode if shes at the GIS full time.

    You gotta get yourself a shapefile of Argentina too but here should help you with that. Some simple map algebra should be able to isolate one polygon from the bigger map but a quick try there and I'm getting an error (but problem solving is half the fun in it!)




  • Hiya Flamed Diving - from what i make you, you need to use the Spatial Analyst tool to do a raster selection of particular data within the attribute table. If you use the raster calculator, you could select the field for the particular country you want and the field containing the data you wish to portray.

    Is that what you mean?


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  • I think so...

    The way that the data is arranged is by co-ordinates. So, what I would like to do is retrieve all the data for one political entity, like Ireland. In addition, if I could get a map of just Ireland with all the data presented graphically, that would be great.




  • Are there any free online guides that people could recommend?




  • Yeah, but there is such a map provided by the website. Is there a way of focusing on one country, to flesh out the different climates within this country? Can the data for one country only be cut out of the dataset?


    Hi, is this what you are trying to achieve? Here the climate data for Argentina has been extracted.

    If you tell me what software and version (ArcView 3.2, ArcGIS 9.1, Mapinfo 7.5 for example) you are using I'll explain how to do it.


    argentina.jpg




  • That is perfect. I will start work on it again next week, so I will check the university computers to see which it is, though I am sure it is Arcview 3.2.




  • That is perfect. I will start work on it again next week, so I will check the university computers to see which it is, though I am sure it is Arcview 3.2.

    Assuming it's ArcView 3.2 these steps will get you to where you want to be.


    1. Download the file and unzip. All your data is now in a folder called 1901-1925.

    2. Open the Legend.txt file in Notepad. Use Edit-Replace to change the ... to a single comma.

    3. Now insert a new line at the start of the Legend.txt file "Key,Climate". Save and close.

    4. Start ArcView 3.2 with a new View and add the 1901-1925.shp file.

    5. Click on the Tables icon and click Add. Change the filetype to Delimited Text and select legend.txt from the 1901-1925 folder. When you click OK the legend table opens. You can see you have two fields, the Key and the Climate type.

    6. Now open the 1901-1925.shp table. Click on the Key field in the legend.txt table. Then click on the Gridcode field in the 1901-1925 table. Then click the Join icon. The Climate field is now joined to the shapefile.

    7. To make the join permanent first bring View1 to the front and select Theme-Convert to Shapefile. Save as Climate.shp in the 1901-1925 folder. Select Yes at Add shapefile as theme to the view?

    8. Now you have Climate data but it remains unrelated to national boundaries. To resolve this you need a national boundary shapefile. Such a file ships with ArcView 3.2, if installed it will be located at ESRI\ESRIDATA\WORLD\Country.shp. In case you're unable to source it locally I've uploaded the shapefile to http://rapidshare.com/files/367575306/Country.rar.html.

    9. Add Country.shp to your View. As this shapefile has an associated .avl (ArcView Legend) file, it will open with a default legend. As this is unrequired double click on the Country.shp legend to open the Legend Editor. Change Legend Type from Unique Value to Single Symbol and click Apply.

    10. Now open the Country.shp table. Select Table-Properties and set Visible to off for all fields except Country_Name. Click OK. You now have two shapefiles of interest. Country.shp, which contains your national boundary polygons, and Climate.shp, which contains your climate data.

    11. Now Select File-Extensions, select Geoprocessing and click OK. Select View-Geoprocessing Wizard, then select the intersect two themes radio button and click Next.

    12. For Select input theme to intersect choose Country.shp, for Select an overlay theme choose Climate.shp. For Specify the output file navigate to your working folder and call the output ClimateByCountry.shp and click Finish. This may take a few minutes but when completed the ClimateByCountry shapefile will be automatically added to your view.

    13. ClimateByCountry.shp consists of each country divided into its constituent climate type regions. You can select out any country and convert it to separate shapefiles if required.

    14. You will also need to create a legend. Double click on the ClimateByCountry.shp legend. In the Legend Editor choose Unique Value for Legend Type, select Climate for Values Field. You can change the colour for each symbol to those shown on the classification charts if required.




  • Brilliant, I can't wait to try it. Thanks!




  • I got as far as point 6. Where is the Join button?




  • I got as far as point 6. Where is the Join button?

    The Join Button is highlighted below.

    Join_Button.jpg




  • :) Hey Guys,

    Can someone please recommend a evening/night/weekend course in GIS around the Dublin area? Looking online but can't find anything suitable. Alternatively, I would consider an online course if someone could recommend one. Any help will be appreciated.




  • Pulling my hair out here! Working on a project where by I have layers of digitised shapefiles and images all set to the projection IRE Transverse Mercator. I want to add in a Raster Dataset, which would enable me to undertake a viewshed/zone of theoretical visibility. (proposed wind turbine).

    When I add the dataset - it doesn't have a projection system assigned and doesn't attach to the dataframe projection. I can't seem to figure out how to set it to the same projection so that all layers sit on top of each other - as they should.

    Any advice?!


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  • Cork_girl wrote: »
    Pulling my hair out here! Working on a project where by I have layers of digitised shapefiles and images all set to the projection IRE Transverse Mercator. I want to add in a Raster Dataset, which would enable me to undertake a viewshed/zone of theoretical visibility. (proposed wind turbine).

    When I add the dataset - it doesn't have a projection system assigned and doesn't attach to the dataframe projection. I can't seem to figure out how to set it to the same projection so that all layers sit on top of each other - as they should.

    Any advice?!

    It appears to me that your problematic raster dataset isn't georeferenced and hence lacks the information required to align it with your other projected datasets.

    Right click on the raster in the table of contents. Select Zoom To Layer (assuming ArcGIS 9.*). Zoom into the top-leftmost pixel and place the cursor over its top left corner. Does the coord display in the bottom right of the screen say approximately 0,0? Now measure the height and width of a single pixel. Are both one map unit in size?

    If the answer to each question is yes then your raster needs to be georeferenced.

    ArcGIS is assuming that the coordinates of the centre of the top left pixel of the raster is 0,0. It's assuming that the horizontal and vertical distance each pixel represents on the ground is 1 map unit. Finally it's assuming that the rotation about the X and Y axes is 0.

    The correct info should be contained in a World file associated with the raster. A jpg should have an associated jpw file. Likewise a tiff should have a tfw. Such a file can be generated using the Georeferencing toolbar.




  • DLz wrote: »
    :) Hey Guys,

    Can someone please recommend a evening/night/weekend course in GIS around the Dublin area? Looking online but can't find anything suitable. Alternatively, I would consider an online course if someone could recommend one. Any help will be appreciated.

    I know DIT run a brief evening course. Personally, looking at the content and cost, unless you need to get the cert, I'd just buy a load of books off Amazon.




  • It appears to me that your problematic raster dataset isn't georeferenced and hence lacks the information required to align it with your other projected datasets.

    Right click on the raster in the table of contents. Select Zoom To Layer (assuming ArcGIS 9.*). Zoom into the top-leftmost pixel and place the cursor over its top left corner. Does the coord display in the bottom right of the screen say approximately 0,0? Now measure the height and width of a single pixel. Are both one map unit in size?

    If the answer to each question is yes then your raster needs to be georeferenced.

    ArcGIS is assuming that the coordinates of the centre of the top left pixel of the raster is 0,0. It's assuming that the horizontal and vertical distance each pixel represents on the ground is 1 map unit. Finally it's assuming that the rotation about the X and Y axes is 0.

    The correct info should be contained in a World file associated with the raster. A jpg should have an associated jpw file. Likewise a tiff should have a tfw. Such a file can be generated using the Georeferencing toolbar.

    Thank you!

    Yes, it is lacking georeferencing - under properties/source it is listed as Spatial Reference <undefined>. However the coordinates do not seem to be set at 0,0 as you described above. Units are unknown but there is a reference point there?!

    How do you generate this file.




  • Cork_girl wrote: »
    Thank you!

    Yes, it is lacking georeferencing - under properties/source it is listed as Spatial Reference <undefined>. However the coordinates do not seem to be set at 0,0 as you described above. Units are unknown but there is a reference point there?!

    How do you generate this file.

    As you know a raster is a 2D matrix of cells. However, without georeferencing ArcGIS has no idea where within a spatial reference it is positioned, how it is orientated or how big it is.

    So georeferencing and spatial reference are not the same thing. Georeferencing is actually the process by which a raster dataset is aligned with a spatial reference, ie a map coordinate system.

    Once a raster has being georeferenced you can set the spatial reference to which it has being registered in ArcCatalog.

    It seems to me that there are two possibilities.

    1. Raster is not georeferenced to any spatial reference.
    This would be the case if, as described before, the top-left cell of the raster had coords 0,0 and each cell was 1 map unit x 1 map unit in size.

    2. Raster is georeferenced but to a different spatial reference system.
    This may be the case if the raster is positioned differently than above and each cell size is a multiple or fraction of 1. Here, the raster has being aligned with a spatial reference different to that being used in your project but the spatial reference for the dataset has never set in ArcCatalog.

    To decide which case it is you should answer the following questions.

    A) What are the coords of the top-left cell of the problematic raster.
    B) What is the size of each cell in map units.
    C) In Windows Explorer check what auxiliary file types (*.aux, *.xml, *.tfw etc) are associated with the raster.
    D) In ArcCatalog check the Spatial Metadata of the raster. Its spatial reference may be stated here.

    You can deal with the actual georeferencing, if required, after it is decided what case you are dealing with.




  • Thanks for your insight!




  • As you know a raster is a 2D matrix of cells. However, without georeferencing ArcGIS has no idea where within a spatial reference it is positioned, how it is orientated or how big it is.

    So georeferencing and spatial reference are not the same thing. Georeferencing is actually the process by which a raster dataset is aligned with a spatial reference, ie a map coordinate system.

    Once a raster has being georeferenced you can set the spatial reference to which it has being registered in ArcCatalog.

    It seems to me that there are two possibilities.

    1. Raster is not georeferenced to any spatial reference.
    This would be the case if, as described before, the top-left cell of the raster had coords 0,0 and each cell was 1 map unit x 1 map unit in size.

    2. Raster is georeferenced but to a different spatial reference system.
    This may be the case if the raster is positioned differently than above and each cell size is a multiple or fraction of 1. Here, the raster has being aligned with a spatial reference different to that being used in your project but the spatial reference for the dataset has never set in ArcCatalog.

    To decide which case it is you should answer the following questions.

    A) What are the coords of the top-left cell of the problematic raster.
    B) What is the size of each cell in map units.
    C) In Windows Explorer check what auxiliary file types (*.aux, *.xml, *.tfw etc) are associated with the raster.
    D) In ArcCatalog check the Spatial Metadata of the raster. Its spatial reference may be stated here.

    You can deal with the actual georeferencing, if required, after it is decided what case you are dealing with.

    Still having problems with this. Happening to me again in another project now, I am obviously doing something wrong! I have a standard "Counties" file from the CSO and a Corine dataset file downloaded. I have set the projection of both to ITM95, but they are sitting miles apart! Both seem to have the projection set ok. Any ideas?

    Also, does anyone have any good "free" or low cost websites for datasets? Would be very useful!




  • Cork_girl wrote: »
    Still having problems with this. Happening to me again in another project now, I am obviously doing something wrong! I have a standard "Counties" file from the CSO and a Corine dataset file downloaded. I have set the projection of both to ITM95, but they are sitting miles apart! Both seem to have the projection set ok. Any ideas?

    Also, does anyone have any good "free" or low cost websites for datasets? Would be very useful!

    Is the actual projection of both datasets ITM95?

    You say that you have "set" the projection of both to ITM95. What do you mean by this? Have you just gone to ArcCatalog and reset the datasets XY coordinate system to ITM95 from their actual coordinate systems.

    To actually "set" a vector dataset to a certain coordinate system use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project.

    Likewise, for a raster dataset use ArcToolbox-Data Management Tools-Projections And Transformations-Raster-Project Raster.

    Can you provide links to the datasets you are working with?




  • Is the actual projection of both datasets ITM95?

    You say that you have "set" the projection of both to ITM95. What do you mean by this? Have you just gone to ArcCatalog and reset the datasets XY coordinate system to ITM95 from their actual coordinate systems.

    To actually "set" a vector dataset to a certain coordinate system use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project.

    Likewise, for a raster dataset use ArcToolbox-Data Management Tools-Projections And Transformations-Raster-Project Raster.

    Can you provide links to the datasets you are working with?

    I was using the Arctoolbox -data management tools - raster projection for the files. So both have the same projection in the source information. I will check for a link to files tomorrow, don't have them with me at home! Really appreciate your help, I am obviously doing something wrong that it keeps cropping up this way. One dataset is just sitting to the bottom left of the other one. Grr!!




  • Ok finally! For example, I am using a shapefile from the CSO free data, the National Monuments download from here and a Corine file from here - say the first one for example. The National Monuments and CSO layer overlay ok, but the Corine data is floating off to the north east! (all projections set to ITM95). I have attached a pic to try explain!


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  • Cork_girl wrote: »
    Ok finally! For example, I am using a shapefile from the CSO free data, the National Monuments download from here and a Corine file from here - say the first one for example. The National Monuments and CSO layer overlay ok, but the Corine data is floating off to the north east! (all projections set to ITM95). I have attached a pic to try explain!

    Worked perfectly for me. I'm not sure what you're doing wrong so I'll just outline what I did. The steps are all practically the same.

    A) CSO Cities/Towns
    Step A1. Download this file and rename it to CSO_ING.shp. I correctly assumed that this shapefile is in Irish National grid. In ArcCatalog, right click on CSO_ING.shp and select Properties. On the XY Coordinate System tab choose Select, go to Coordinate Systems\Projected Coordinate Systems\National Grids and choose Irish National Grid.prj. In the next step ArcGIS will now automatically know this shapefile's coordinate system.

    Step A2. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from ING to WGS84. For Output Coordinate System go to Coordinate Systems\Geographic Coordinate Systems\World and select WGS84.prj. For Geographic Transformation use TM65_To_WGS_1984. Call the output file CSO_WGS84.shp.

    Step A3. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from WGS84 to ITM. For Output Coordinate System go to Coordinate Systems\Projected Coordinate Systems\National Grids and select IRENET95 Irish Transverse Mercator.prj. For Geographic Transformation use IRENET95_To_WGS_1984_1. Call the output file CSO_ITM.shp.


    B) National Monuments
    Step B1. Download this file and rename it to Archaeology_ING.shp. As a .prj file is included, ArcGIS knows that the projected coordinate system is Irish National Grid.

    Step B2. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from ING to WGS84. For Output Coordinate System go to Coordinate Systems\Geographic Coordinate Systems\World and select WGS84.prj. For Geographic Transformation use TM65_To_WGS_1984. Call the output file Archaeology_WGS84.shp.

    Step B3. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from WGS84 to ITM. For Output Coordinate System go to Coordinate Systems\Projected Coordinate Systems\National Grids and select IRENET95 Irish Transverse Mercator.prj. For Geographic Transformation use IRENET95_To_WGS_1984_1. Call the output file Archaeology_ITM.shp.


    C) Continuous urban fabric
    Step C1. Download this file and rename it to Corine_Lambert_AEA.shp. As a .prj file is included, ArcGIS knows that the projected coordinate system is Lambert_Azimuthal_Equal_Area.

    Step C2. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from Lambert_AEA to WGS84. For Output Coordinate System go to Coordinate Systems\Geographic Coordinate Systems\World and select WGS84.prj. For Geographic Transformation use ETRS_1989_To_WGS_1984. Call the output file Corine_WGS84.shp.

    Step C3. Use ArcToolbox-Data Management Tools-Projections And Transformations-Feature-Project to change the coordinate system from WGS84 to ITM. For Output Coordinate System go to Coordinate Systems\Projected Coordinate Systems\National Grids and select IRENET95 Irish Transverse Mercator.prj. For Geographic Transformation use IRENET95_To_WGS_1984_1. Call the output file Corine_ITM.shp.


    Now you will have three datasets, all in IRENET95 Transverse Mercator projection. Add all three to a new map document and everything should be OK.

    I've also placed the output IRENET95 shapefiles here.


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