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Thread: A question on depicting ship routing in ArcMap 10.1

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    David Schwartz
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    Default A question on depicting ship routing in ArcMap 10.1

    Hello,

    I'm working on a project depicting maritime Search and Rescue response. Now in a prior basic incarnation I was able to show the ranges of vessels as buffer depicting as an operational radius with no accommodation for intervening landmasses. Now for the full version of this project I was wondering if this was possible to do so that actual range and not a hypothetical one can be shown? I was initially suggested building a network analyst network on the water to show an actual route based on a set of starting principles, but I wonder if there is a better way.

    Thank you,

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    John Fry
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Hello DaFelix78, the best way to create ranges of vessels that take into account is using a cost distance input raster. Using the tool 'Cost Distance in the spatial analyst toolbox, put in an input of water as the "input cost distance" raster. In your raster the water pixels=1 and the land=0. This means that the vessel cannot go on land pixels and will take into account for the land. To create a cost distance raster such as this, what I did long ago (sorry if I can't remember the exact steps) was to download a land polygon (http://www.arcgis.com/home/item.html...933618e3815dd2), create a large polygon that overlaps your land in your AOI, union the two, create a value field, give the water section of the polygon a value as "1" and the land as "0", run the feature to raster tool. Save the raster as a 2-bit FGDB raster to save some space.

    Now, you have a basic cost raster depicting land and water. Now if you want to refine your cost raster input, you could use inputs such as bathymetry, wave height, winds, currents, etc, as areas that your vessel cannot go. You would make those areas that your vessel cannot go/an impedance as "0" values.

    Below, is an example of a farthest on circle tool. The tool allows a user to understand where a vessel could go in "X" time. It's similar to your problem. The tool allows the user to drop a location (as a feature set), input a mask (for my case, it was a water mask with water=1 and land=0), input a speed for the vessel, and then a range for the analysis.

    Click image for larger version

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    The "Farthest on Cost.." tools input is below:
    Click image for larger version

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    The Cost Distance in the 'Time Analysis' section is converting values from distances to amount of time.

    When you run this tool you get an output that takes into account of time and land (Below):
    Click image for larger version

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    I hope this has given you some help.

    John

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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Hello,

    Thank you very much this is pretty much what I was looking for.

    A couple questions from trying to follow the model building portion:
    1) The range and average speed are not inserted shapefiles I'm guessing, buffer for the first and something else for the second. So what are they? Are they values in an excel table or a word file?
    2) I cannot find a farthest on cost tool in ArcMap10.1 though your image makes it look like it should exist, does it go under a new name now or has it been eliminated?

    Thank you,

    David
    Last edited by DAFelix78; 07-03-2013 at 03:45 PM.

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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Oh and a third question: what kind of mask are you deriving from the raster file?

    Thank you once again.

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    John Fry
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    David,

    Sorry for the brief description. I will go in greater detail.

    To answer questions:

    1) The range and speed are string variables that are used in the Calculate Values processes. Here's each of those tools:

    Calculate Value (2)
    This converts the input of range from nautical miles to meters
    Click image for larger version

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    This value is for the input of the buffer tool

    Calculate Value
    This tool converts the input value of kts to meters per hour
    Click image for larger version

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    This output is used in the "Raster Calculator" process and a conditional statement is run, assigning that speed value to all water areas covered by the mask input. To quicken the tool, I assigned the processing extent of the mask to be the area of the buffer output.

    Click image for larger version

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    2) Sorry, I changed the name in the model. The 'Farthest on Cost distance' tool is the 'Cost Distance' tool in the spatial analyst toolbox.

    3) The raster output is a file geodatabase raster.

    Here's a link to the tool http://www.arcgis.com/home/item.html...cdc37a6c0f0bf#. I have not documented it great, but hopefully you can use it as a guide. If that link doesn't work, try searching "farthest on circle".

    Regards,

    John

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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Once again thank you for your assistance. I'm getting this farther along but I keep running into problems getting the calculate value sections to work. In both cases I get an Error 000539 where there is a problem with:
    -File "<expression>", line 1 in <module>
    -File "<string>", line 10 in Convert Knots to MetersPerHour. ValueError: could not convert string to float: %average Speed in knots (kts) for Analysis%

    I did follow what you gave me exactly but Python is not my strong suit (obviously) so I don;t know how it exactly applies to sort it out myself.

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    John Fry
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Did you change the name of any of the items in the model?

    The %average Speed in knots (kts) for Analysis% and %Range for Analysis in Nautical Miles% are referencing the inputs (blue boxes with "p") in the model. If you change the name of the inputs, these need to be reflected in the calculate value tools.

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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    I think that may be it. I will check and get back to you on that since I'm also working a non GIS gig right now.

  9. 07-30-2013 05:07 PM


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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Thank you I finally got this mostly working and it seems to be doing what I want, mostly. But once again I have a couple questions to try to define things.

    -My output are not radii but instead a set of blocks, looking more like raster cells filling a square and not a layered circle like in your first post. I do have values for range and corresponding values for buffer so what wrong?
    -When my bases are on the coast I get great range values but if they are in an island chain, like the islands in the Alaskan Panhandle they get contained and show no exists to open water. Is it possible to make a raster that would show smaller cells since the size of cells is cutting off the water?

    But thank you since this is taking me the right direction.

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    John Fry
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    Felix,

    My apologies for the late reply in this thread. Could you post a picture of your result? It could be a problem with your processing extent or the reclassify process.

    It is definitely possible to make cells with smaller cell sizes. You could define a smaller AOI, say AK panhandle ocean areas. For instance, download a land polygon (http://www.arcgis.com/home/item.html...933618e3815dd2) or one with a better coastline for your AOI) and create a large rectangular polygon that overlaps your land in your AOI, union the two (land and rectangular polygon), create a value field, give the water section of the polygon a value as "1" and the land as "0", and run the feature to raster tool with cell sizes of a smaller value (if your aoi is small, something like 10m could work). Save the raster as a 2-bit FGDB raster to save some space. Then use this as your mask to run the farthest on circle tool.

    Another process you could add to the tool is instead of having your land mask of just water and land areas, you could use a bathy file as your input and run a raster calculator to find areas deeper than the draft of the ship.

    In the image below my mask has changed to a bathy file. I am running a raster calculator tool on the bathy file and finding what areas are deeper than the draft of the vessel. The output is a "1" for values suitable for boat travel and "0" for not suitable (too shallow, or land). I am using a File Geodatabase Raster of an export of GEBCO (http://www.gebco.net/) as the input bathymetry. It's got pretty big cells so its probably not to useful in your case, but you can readily get bathymetric data and coastal models for (http://www.ngdc.noaa.gov/mgg/bathymetry/relief.html) that could be used.
    Click image for larger version

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    Click image for larger version

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    Hope this helps.

    John

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    David Schwartz
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    Default Re: A question on depicting ship routing in ArcMap 10.1

    For starters the results have changed. Well that and I walked away from this to do some other work and have a adviser acceptable alternative plan. But the results since then changed from irregular polygons to world wrapping distances well outside the realm of the possible for the small boats.
    Click image for larger version

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    With the corresponding text when this is run saying:

    Start Time: Sat Sep 28 17:18:18 2013
    The input raster maximum (26295246) is out of range.
    To ensure a correct reclassification, edit ranges or use a different precision settings in the Reclassification dialog box
    .
    Succeeded at Sat Sep 28 17:18:55 2013 (Elapsed Time: 37.00 seconds)
    The AOI, as you can see is a good size for me but I can make a smaller one for this project. As for the Bathy, well if I can just get this to work it should be effective enough.

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