Spectrum Spatial (SSA/LIM)

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data precision/accuracy difference

  • 1.  data precision/accuracy difference

    Posted 07-03-2019 05:54
    Hi,

    I have created a map in Pro and added it to SSA via the uploader tool.  when displayed over a WMS basemap the data is slightly 'off' as though there was some underlying projection/bounds issue.  However, I noticed that if I created the same map using the same layers/tables from within the spatial manager all the data lines up perfectly to the same WMS basemap.  In Pro all the data fits perfectly too.

    Any ideas why it is different using the uploader tool?

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    Nick Hall
    Mapchester LTD
    nick.hall@mapchester.co.uk
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  • 2.  RE: data precision/accuracy difference

    Moderator
    Posted 07-04-2019 02:25
    Hi Nick,

    Thank you for seeking out help to your query on the Knowledge Community.

    We have seen this misalignment issue previously too where someone was seeking for a quick help/workaround. That time we understood that Maps that had layer added directly from Spectrum Spatial were not facing any misalignment which you already have found out.

    That previous discussion concluded as soon as the user found out the workaround and we could not investigate the root cause due to lack of sample data. In order to investigate more on this, we require some sample data to see this behaviour in our copy of SSA which will help us in answering your query in the best way possible. If you think that the data that I am asking you to share is quite confidential and can not be disclosed on this public site, we can share a personalized link for the same or can create a support ticket for one to one communication.

    The end result that comes out after the investigation will help the community anyways!

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    Nalin Mathur
    Pitney Bowes Software India PVT. Ltd
    Noida
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  • 3.  RE: data precision/accuracy difference

    Posted 07-05-2019 05:04
    Nalin,

    Thanks for the reply.  I will ask the client and let you know.

    Thanks

    Nick

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    Nick Hall
    Mapchester LTD
    nick.hall@mapchester.co.uk
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  • 4.  RE: data precision/accuracy difference

    Pitney Bowes
    Posted 07-08-2019 15:56
    Nick,

    ​Your question is interesting. I can offer some ideas but I cannot yet see how the difference could be the map uploader.
    Here's some information which might get us closer to the problem.
    The Map Uploader, you may know but others may not, only transfers map information such as styles and layer order. . It does not touch the data in any way. It tries to find, on the server, the data tables used in MapInfo Pro. For some people, the data they use in Pro is actually the same files that the server will use. In other environments, the data on the server is secured and not available to Pro. However, in all cases, the uploader is only creating references to where the data is found. It never touches the data.
    While rare, it is possible that the data used by Pro might be different than what the uploader found on the server. It could even be in  a different projection.  All that can be determined via Spatial manager. and looking at the files on the server.
    However, once uploaded, the data on the server is the same for Spatial Manager as it is for the Analyst application or any other scenario.  Using Spatial Manager directly without the uploader should make no difference. The Named Table points to the data and the projection information is in the data, which is a TAB file in this case, I believe.  Since we don't display your WMS base map in Spatial Manager, I am not sure how you are seeing things line up or not in Spatial Manager.

    When it comes to Analyst or any application using a base map, then it is possible that Spectrum Spatial will have to reproject the data on the fly to match the base map. Is this WMS map a British National Grid map? Is it coming from Spectrum Spatial or another source?  Is the WMS a raster or vector source? If from another source it is possible that the source does not use the NTV2 transformation corrections that we use. If the WMS is coming from Spatial, then it would use the same transformation code.  Again, this does not explain any difference between a map uploaded layer or manually configured.  Also MapInfo Pro uses the same NTV2 transformation system that we do. (both can be disabled if we think that might be relevant).
    Also note that the way MapInfo Pro renders (one image for the entire map window) vs Spectrum Spatial Analyst (like most web mapping, asks for map images in pieces) it is possible that there is an issue with the matching of the small squares being rendered.

    Maybe this information is useful but in either event I would heavily suggest you set up a case with support and if we can get something to reproduce or even a link to the customer site, I am sure we can figure out what is going one.
    The map uploader part still stumps me.  Even though it writes the projection of the map information from MapInfo Pro into the named map, Analyst ignores that information. The map projection is chosen by the base map.




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    Eric Blasenheim
    Spectrum Spatial Technical Product Manager
    Troy, NY
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