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GIS Help Clinic
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20-03-2010 4:15pm#1
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Flamed Diving wrote: »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
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Flamed Diving wrote: »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.
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Flamed Diving wrote: »I got as far as point 6. Where is the Join button?
The Join Button is highlighted below.
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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.0 -
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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.0 -
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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.
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.0 -
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YoureATowel wrote: »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. 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!0 -
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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. 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.0 -
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Rowley Birkin QC wrote: »I'm also trying to export .KMZ files from Google Earth into ArcMap. As I understand it these are in WGS84 by default so I'm skipping the first step as listed above in post #31. I can't get them to sit correctly on my map though when I finish the process and and convert them to ITM.
Any ideas?
You only need to use Step 3 from Post #31, ie 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.
However, if you are combining data from Google earth .KMZ files with data from other sources than you may encounter problems due to the varying accuracies of the datasets. For example, I have noticed discrepencies of 20 - 100 meters between lines digitised from Google Earth and those same features on 40cm orthophotography.
The image below shows road centerlines of Marino, Dublin digitised from Google Earth and sumperimposed on the commercially available 40cm ortho. The discrepency here is in the order of 70m.
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I'm starting to go a bit cuckoo at the moment.
I've a project to work on that involves using LiDAR in GIS. Basically I've to make a hillshade from that and deduce the various features - sounds easy enough...except I'm really stuck and now my data is coming out all pixelated and even though it looks like it's 3D from afar when you zoom in to get a closer look it's just flat...
Would anyone have any ideas?
First of all I wouldn't be worried if your hillshade appears to be "just flat" when you zoom in. That's obviously going to happen. It's the same as if you try to watch TV from a distance of 5cm, you're just going to get a pixelated version of what appears normal at 5 meters.
Ensure that the resolution of your hillshade is not smaller than the resolution of the input surface generated from your LIDAR data. It's probably preferable that they're the same resolution.
I generated the following surface from public domain LIDAR data, it has a resolution of 5m.
The surface was then used to create this hillshade, also with a 5m resolution.
Look what happens when I use a 1m resolution.
This is at 25m.
So dramatically increasing or decreasing the hillshade resolution from that of the input surface produces unsatisfactory results.
Now lets return to the 5m resolution hillshading. Even though this random example isn't exactly ideal I can still easily pick out the rivers, roads and even lakes
By classifying the surface, making it transparent and placing it over the hillshading you can get even more dramatic results.
A 3d scene, incorporating small scale raster mapping of the same area, can also be used to confirm suspected features on the hillshading.
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I'm a little stuck on the GIS myself (i.e. I've no experience of it and I'm pretty stuck).
I'm trying to map a salt marsh in Co. Clare, so I sent off for the corine data from the EPA, got it in the post and that's where the problems start.
Here's what I've managed to get done:
Now I don't know what else to do or what I should be looking out for.
I've also got GPS coordinates to put into it as well so, that's another issue.0 -
I'm a little stuck on the GIS myself (i.e. I've no experience of it and I'm pretty stuck).
I'm trying to map a salt marsh in Co. Clare, so I sent off for the corine data from the EPA, got it in the post and that's where the problems start.
Here's what I've managed to get done:
Now I don't know what else to do or what I should be looking out for.
I've also got GPS coordinates to put into it as well so, that's another issue.
I can't see your image there El Siglo!
Just to note.. you can actually download the Corine 2006 datasets online and then project them following the steps outlined in this thread from Youratowel - I've done this for all of the Corine datasets in the past few weeks.
Out of curiosity - what kind of timeframe did it take to get the data from the EPA? Was there any cost involved and what co-ordinate system did they provide them in?
When you say GPS Co-Ordinates, do you need to put a point/shapefile at these locations?0 -
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I'm a little stuck on the GIS myself (i.e. I've no experience of it and I'm pretty stuck).
I'm trying to map a salt marsh in Co. Clare, so I sent off for the corine data from the EPA, got it in the post and that's where the problems start.
Here's what I've managed to get done:
Now I don't know what else to do or what I should be looking out for.
I've also got GPS coordinates to put into it as well so, that's another issue.
What software are you using? Arcview 3.*, ArcGIS, MapInfo?0 -
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It was ArcGIS 9.2, it was on a college computer so it had the full package. I think? Yeh it was because it was on a computer with windows xp.
This might give you a rough idea of what to aim for.
I downloaded the data from the EEA website, projected it to Irish National Grid. The extent of the files make them quite unwieldy so I then selected out the data relevant to the study area.
Next I began to group similar layer types. For example, I grouped Intertidal Flats, Water Courses, Water Bodies and Estuaries together and symbolised all four layers the same way.
In the end I had consolidated the multiple layers that cover the study area into 9 new layers. Salt Marshes, Agriculture, UrbanFabric, Water Bodies, Industrial\Commercial, PeatBogs, Grasslands\Heathlands, Forests and InlandMarshes.
I used Google Earth to digitise the roads and determine the road, lake, town etc names. I imported this linework into ArcMap and styled it accordingly.
The next stage was to add a hypothetical point file. I made the assumption that each point reflects a scientific measurement of some type made at a specific location within the salt marshes.
Adding XY Data to a map.
1. Place all your Easting, Northing, Measurement data into a comma delimited text file. The first line in this file should be the Field Name of the subsequent data. The file should look something like this.
2. Add the textfile to ArcMap. Right click on the textfile name in the table of contents and select Display XY data.
3. For X Field choose Easting, for Y Field choose Northing. For Coordinate System of Input Coordinates, click Edit, the Select and navigate to the required coordinate system, in this case Irish National Grid. Click Ok to the Object-ID Field warning.
4. The XY Events are then added. You can now symbolise the points accordingly. I used Graduated Symbols based on the Measure field. The larger the Measure value, the larger the symbol will appear on the map.
Finally I added a Legend, North Arrow and a Scalebar using the Insert menu.
It might also be wise to state where you sourced your data.0 -
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What exactly are you trying to do? 
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