Overview

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GEDI Overview

GEDI is an editor that assists you in ground truthing scanned text documents. Its basic structure involves two types of files, an Image file, and a corresponding .xml file in GEDI Format (see below). A series of image files stored in the same directory (folder) can be opened simultaneously and the interface maintains a one to one correspondence with XML files of the same name, in same or another directory. When you begin ground truthing an image, you can configure the interface to allocation the creation of different types of zones, each of which may have a custom set of “attributes”.

GEDI allows users to enter information at both the page level and at the zone level. Zones are typically used to mark the locations of physical regions on the page, such as text, signatures, logos, etc. Different zone types should be used to label different types of page elements. Information about a particular zone or page can be entered by setting values for attributes. Pages and zone types can have any number of attributes associated with them, and each instance of a page or zone can have its own values for the attributes. For labeling text, the pre-defined DL_TEXTLINEGT zone type can be used which manages predefined attributes for contents and character or word offsets within the zone. For specifics about any particular feature of GEDI, please select it from the table of contents to the left. Some topics have sub-topics and can be expanded by clicking on the plus sign next to them.

If you are already familiar with GEDI, you may still want to take a look at Appendix C: Modification History.

GEDI Philosophy

Before beginning any annotation, it is useful to understand the GEDI Philosphy for annotation.

When the user annotates an image, GEDI stores the information in an XML file in the following format:

    <?xml version="1.0" encoding="UTF-8"?>
    <!--GEDI was developed at Language and Media Processing Laboratory, University of Maryland.-->
    <GEDI xmlns="http://lamp.cfar.umd.edu/GEDI" version="1.0">
        <USER name="Elena" date="5/23/2008 17:24" dateFormat="mm/dd/yyyy hh:mm">    </USER>
        <USER name="Orri" date="6/11/2008 12:52" dateFormat="mm/dd/yyyy hh:mm">    </USER>
        <DL_DOCUMENT src="sample.tif" docTag="xml" NrOfPages="3">
            <DL_PAGE gedi_type="DL_PAGE" src="sample.tif" pageID="1" width="1728" height="2292">
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="2" col="1285" row="269" width="166" height="335" orientationD="16.169" contents="" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="3" polygon="(151,253);(274,274);(610,294);(561,331);(540,375);(312,380);(255,414);(109,404);(76,363);(107,349);(113,300)" contents="" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="4" col="208" row="500" width="245" height="40" contents="" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="5" col="214" row="626" width="494" height="35" contents="To: Mr. A. Sadovnick" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="6" col="214" row="704" width="98" height="40" contents="" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="7" col="396" row="706" width="303" height="34" contents="" offsets="" segmentation="word"> </DL_ZONE>
                <DL_ZONE gedi_type="DL_TEXTLINEGT" id="8" col="728" row="165" width="296" height="259" contents="" offsets="" segmentation="word"> </DL_ZONE>
            </DL_PAGE>
            <DL_PAGE gedi_type="DL_PAGE" src="sample.tif" pageID="2" width="2592" height="3300">        </DL_PAGE>
            <DL_PAGE gedi_type="DL_PAGE" src="sample.tif" pageID="3" width="2592" height="3300">        </DL_PAGE>
        </DL_DOCUMENT>
    </GEDI>

The GEDI represents a document as consisting of pages, and on each page a set of zones, and for each zone a set of attributes. The types of zone, and the user attributes which describe them are fully configurable in the interface. Each zone does have a set of “required” attributes which include 1) Zone ID, 2) GEDI-type, and 3) the coordinates of the zone – row, col, height and width for normal zones, an additional orientation attribute for oriented zones, and a list of points for polygonal zones.

The interface itself provide many different tools to help manage and maintain this metadata including function keys, drop down lists, color coding of attributes, support of multiple languages (including bi-text) etc. Details and lessons learned are found throughout this help document.

As one additional introduction, here are some details on how the data is stored in the GEDI XML format. Please refer the example above:

The main tag is a GEDI tag, and it has two types of tags within it. It has one USER tag per user that has modified it (which includes the name of the user, the data modified, and the format of the date modified [mm/dd/yyy hh:mm is the default]), and the other is the DL_DOCUMENT tag, which represents the document, and includes information such as the number of pages of the image being worked on and the system path of the image. The DL_DOCUMENT tag has within it one tag per page of the image being worked on (in most cases, one, but if you have a multipage tiff, it will be more than one), whose attributes include the height, width, page id (1 through however many pages), and the system path of the image.

Within each page tag, there are a number of DL_ZONE tags, which correspond to the zones drawn on the image in GEDI. If the user has turned on parent-child mode to draw any of the zones, some of the DL_ZONE tags will have other DL_ZONE tags within them (these are the zones drawn inside the parent zone).

If the zone is a DL_TEXTLINEGT zone, it will also include the contents, offsets, and segmentation. Of course, the user is free to add attributes to the page, or to any of the zone types. These will also be included in the xml file.