[GWP] Display selected objects only?

Hi,

using Geo Web Publisher, is there a way or a workaround how to display selected objects only?

I am using Geo Web Site with Map Viewer now, but my question is more general: If there is a group of identified objects (selected in MapViewer or a result of search etc.), is there a tool / way / API how to isolate them and to display them separately without their original layer(s)? The object can reside on different layers, not always in one only.

The reason my question is results from user query can be plenty of quite complex objects, so to highlight them only is not enough if also the rest of layers content is displayed. It would be nice to have e.g. MapViewer API to copy an element identified by its rendition id to own overlay layer, but I have not found function.

With regards,

  Jan

  • Hello Jan

    Without considering the API, three features can be utilized to assist in visual isolation of search results from a *single* layer.

    From within the Site Author's Search object:

    -Select Graphical Elements:
    (available, when the map layer is set as 'selectable', within the Map Author)
    This will allow the items in question to be selected, and thus to appear in the highlight color

    -Show persistent symbols:
    This would allow display of an additional raster symbol at a set (persistent) pixel size, denoting the object.

    -Layer Display Change as a Result of the Search:
    This allows append/override of the current layer display, as a result of the search

    These features may not allow you to achieve the goal stated, when your results are obtained from *multiple* graphical source layers.
    Can you elaborate on how you are arriving at this presently?

    thanks,
    Nels

  • Hi Nels,

    thanks for your answer.

    Unknown said:
    From within the Site Author's Search object:

    The functionality of the standard Site Author is not enough and I assume we will add own custom objects, but so far it seems the problem is not Site Author itself, but lack of functionality in GWP and ActiveX APIs.

    Element highlight is not bad, but only highlight color can be set (as far as I know), nothing else (e.g. line width). If a published data are rich, imagine e.g. 5 - 10 communication parallel wires with annotations in different colors (resymbolization based on a specific feature, e.g. type or owner), it's complicated to find the good highlight color, which will be visible for users.

    Persistent symbols cannot be used in this case, because typical search will be more topological / tracing oriented, so the result will be often like "show me a trace from point A to B using only specified type of cable".

    Layer Display Change as a Result of the Search: It provides no extra functionality, because it works on a layer only, so it leads back to the problem with highlight only, no isolation is possible.

    Unknown said:
    These features may not allow you to achieve the goal stated, when your results are obtained from *multiple* graphical source layers.

    That's true, the dependency of available tools on one layer only is frankly annoying. But I assume (and hope ;-) it will be possible to modify the delivered code to work with more layers together. It will be defined what layers belong to the same feature, so fortunately there will be no necessity to develop completely general solution, "only" to work with selected layers as with one.

    Unknown said:
    Can you elaborate on how you are arriving at this presently?

    I am an external consultant on this project, so I don't know all details (and some details are internal and cannot be discussed publicly now). But in general it's about centralization and standardization of GIS system and migration from various sources and solutions.

    A primary contractor, who is responsible for the implementation, has experience plus made some research of both commercial and open source web solutions and what they told me, competitors offer the discussed functionality: e.g. using publishing request with a filter in a query to Oracle Spatial data or by ability to create temporary elements and publish them to a client including support to handle client session information.

    ... so this request landed on my table as the question how it can be done in GWP as it was expected it's possible because other solutions allow it (using different approach) too. So far it seems to me it's not possible to implement such functionality, but I'd like to be sure and to know if some workaround or similar solution was implemented by some other user in the past.

    With regards,

      Jan

  • Hi Jan,

    The MapViewer API could help you to retrieve selected elements and then add new elements as an overlay layer.

    First step is to get selected elements using the "GetSelectedElementsInLayer". You will also need the "GetElementPointsInLayer" to get the list of points (xyz) and the "GetElementTypeInLayer" method to get the type of elements (point, line or polygon).

    The second step is to create new elements using the "CreatePolylineElement" or "CreatePolygonElement" methods. You also have the ability to change the color, line thickness, etc.

    HTH

    Sylvain

    Answer Verified By: Jan Šlegr 

  • Hi Sylvain,

    thanks for your answer. What you recommend is close what I have thought about as the approach I should investigate, so it's good to know this is recommended way. As an alternative I also think about to receive geometry data from server, where they can be extracted directly from Oracle Spatial. Will see what will be simplier with respect the fact the results will be probably often spread over many layers.

    I will see if some combination of transparency, line width and color can be used as a better element highlight solution than original MapViewer simple highlight functionality.

    I have to say there is only one real competitive advantage in my opinion: GWP is able to handle and publish complex symbology including custom line styles used in DGN and DWG (and it's shame it's not supported when XFM is published from Spatial DB), which makes it good tool for rich technical maps. Unfortunately this advantage is lost when a new element has to be created :-(

    With regards,

    Jan