Problems Importing or Exporting

Problems importing or exporting to different formats account for most Technical Support issues. Most such problems are caused by confusion arising from the limitations of legacy formats, especially when importing projected maps. The most confusing situation on import arises when a legacy format unsuited for the saving of projected data (such as .dxf or .shp) is used to save maps projected in an intrinsically user-unfriendly projection such as UTM.

 

On export, it is important to remember that legacy GIS systems such as ArcView and MapInfo are not able to handle all aspects of rich data that may exist within a Manifold project. Any export will inevitably involve manual intervention to simplify the data into those limited forms that the target system can handle. If you are exporting data for use within legacy systems it is your obligation to learn enough about the limitations of those systems to know how data must be dumbed down into something they can handle.

 

Importers do not work correctly or report errors.

 

·      Are you sure you are using the correct importer? Several GIS formats use the same file extension but require different formats. For example, both NIMA NITF and UK Ordnance Survey NTF formats use a ".ntf" extension for files. Files may be described casually and inaccurately as something other than what they are. The generic term "DEM" refers to at least five different formats, each of which requires a different importer.

·      Is the file the format you think it is? Errors occur on web sites that provide files. The USGS web site, for example, has on occasion incorrectly provided FTP access to DEM files that were really SDTS DEM files and vice versa. Directories providing access to "DLG" files will often provide them in SDTS form.

·      Is the file damaged? When working with a downloaded file, try downloading the file again in case an error was introduced during download. On rare occasion files will be damaged when loaded across a local network or when read from a damaged hard disk sector.

·      Has the file been decompressed? Files are often published as compressed archives using "zip" or "GNUzip" or "tar" archival or compression methods. These must be decompressed or unzipped before use with Manifold importers.

·      Has the file been correctly decompressed? When decompressing UNIX tar or tar.gz files with WinZip one must uncheck "TAR file smart CR/LF conversion" in the configuration settings to avoid introducing errors during the decompression process. Other decompression utilities may have similar nuances involved in correct operation.

·      Do you have adequate free space on your hard disk and on the hard disk volume hosting your TEMP file? You should have free space that is three times the size of the imported file.

·      Have you selected the right importer? Some GIS data files do not have extensions and so the right importer must be selected.

·      When importing DLG files, are you sure they are in "optional" DLG format? This is the format imported by Manifold and has replaced the "original" format. DLG optional replaced the original DLG in government usage many years ago. However, on very rare occasions one may still encounter DLG files in "original" format.

·      Files are sometimes provided without extensions when they should have extensions. For example, the 14 CD set of DLG files covering the US that was published by USGS in 1993 contains the DLGs in the form of zipped files. However, when unzipped, the result is files that are named using numbers without a three letter extension, for example SF4RDF04. These must be renamed to add a .opt extension to each file, for example SF4RDF04.opt.

 

Imported drawings appear to be incorrect.

 

·      Is the imported data projected? Projected maps saved in old formats will require manual entry of the required projection formats. See Projections and Legacy Formats .

·      Does the imported drawing represent a geographic drawing? If it is a CAD drawing it will require georegistration to appear in the correct location and scale.

·      If importing a CAD drawing for non-geographic use and the scale is incorrect, read the topic for the importer being used to learn how to set scale when importing.

·      Manifold importers use reasonable default settings for formats but individual drawings may require choices other than default settings depending on the specific nature of the file being imported. Read the Help topic for the importer being used, read any documentation that might accompany the file being imported and try again with different settings.

·      If an imported projected geographic drawing does not match other drawings it may have been published using a different datum. Re-project it using the same datum as the drawings it is to match.

·      Some drawings may be the victim of some fundamentally bad choice made by the publisher that irretrievably damaged their accuracy. Data on the edges of UTM zones in maps published in UTM projection might suffer from this problem. Try to get the data in some other form, preferably unprojected.

·      Some formats very poorly organize objects in drawing. Certain SDTS files, for example, can place large areas in the same drawing where they overlay and conceal smaller areas. Until the larger areas are deleted or moved to a different drawing the areas underneath might not be visible.

 

Imported drawings do not look like original maps.

 

·      Are you sure you are comparing the same thing? GIS systems often have an option to save in different formats. The information saved by the exchange format you are using to import a map might not contain the same formatting information (colors, etc.) as that used by the GIS system to display a highly-formatted map.

·      Formatting applied to the underlying objects drives the appearance of drawings or maps in the original system. This will be different from system to system. Not all exchange formats will convey formatting information in a way that's usable by Manifold. See the Formatting topic for general information and the specific topic for the importer being used.

·      If text or other embellishments do not appear it could be that the GIS system from which you are importing maintains such capabilities in a way that is not translatable into Manifold. See the Help topic for the importer being used.

 

Imported maps do not look like pretty road maps.

 

·      Maps imported from most generic sources will require formatting. Read the Key Ideas topic and the Formatting topic.

 

Imported drawings or images seem empty, do not appear in maps, or appear in unexpected places.

 

·      If the drawing or image does not appear in the map, use Zoom to Fit to make sure all of the data is in view. Select the image or drawing and GoTo the selection and zoom far, far in to make sure you don't overlook anything. It could be that the item is visible in the map but is not in the location expected (and so is far away from the view seen in the window) or is so small (because it has not yet been scaled properly) that it is not obviously visible.

·      Did you import from a geographically aware format? Import from non-geographic formats such as .dxf or .jpg will require georegistration to correctly locate the drawing or image.

·      Did you import a projected drawing or image? If importing from a "dumb" format you may need to manually specify projection information. See the Projections topic.

·      If the imported items appear in a tiny dot off the coast of Africa you have imported from a non-geographic format and must georegister the image or drawing or must manually specify projection information.

·      Are you sure the drawing or image contains the data you think it does? Open the drawing or image within a drawing or image window to see how it looks in its native coordinates. For drawings that appear empty, use Zoom to Fit and change the formatting of points to a large size so that any points will not be overlooked. Drawings that you expected to contain lines and regions might contain only a few points that are so few and so small that the drawing appears empty. Open the drawing's table to see if there are any records.

·      If images appear empty it is possible (but very rare) that they are RGBa images with very high transparency set on each pixel. The pixels are there but are so transparent they cannot be seen. Check to see if the image is an RGBa image. If it is, click OFF the Alpha channel in the Layers pane so you can see the image without any transparency effects.

 

Problems importing or exporting to ESRI .shp "Shapefiles".

 

·      Are you having trouble importing a shapefile that might contain projected data? A recent hack to the shapefile format incorporates projection information but most shapefiles that have been published predate this extension and so do not save projection information. If you use such shapefiles to import projected data you must manually add the required projection information. See the Projections and Legacy Formats topic.

 

Problems importing geocoded data from Excel.

 

·      It's not a good idea to keep databases or database-style lists of records in Excel because Excel does not have the built-in discipline to keep databases neatly organized that is provided by database management programs such as Access. It's easy to go wrong in Excel by creating spreadsheets that are not really database tables, that co-mingle column headings and comments with record information, or that specify unexpected field types. The Manifold geocoded data importer cannot repair a confused data layout in Excel. The best approach to debugging a "database" stored in Excel is to first import it into Access. If you cannot import it into Access it is not a valid database table and Manifold will not be able to import it either. Organize the Excel file so it can be imported into Access. Better still, use Access in the first place.

 

Problems importing geocoded data.

 

·      Is the problem reading latitude/longitude coordinates? Manifold reads all of the common ways of writing latitude and longitude values, but some data sets use such weird formats for latitudes and longitudes that the Manifold importers cannot be adjusted to read them. In such cases the latitude/longitude values must be translated into a standard form. We recommend standard decimal notation where each latitude or longitude consists of a whole degree value followed by a decimal point and decimal fractions of a degree: "38.0852". Latitudes from the Equator to the South pole are prefixed with a minus sign: "-39.0852", as are Longitudes from the Prime Meridian westward to -180 degrees longitude. It's possible to use Manifold to make conversions from really strange formats if you know how to use the transform toolbar. To make a conversion, import the database as a table and then use the transform toolbar operators to copy/translate the latitudes and longitudes into standard form. Token operators will be used, so learn how to use them. You can then export the table and then import it as a geocoded database to create a drawing showing the information it contains as points.

·      Is the problem reading coordinates that are supposed to represent projected data? Read the Projections and Imported Components topic and the Projections book topics. Importing geocoded databases where the coordinates are for some projected coordinate system (such as UTM or Gauss Kruger) is expert-level stuff that involves a host of complications. You'll need to import the geocoded file as abstract coordinates and then manually set the coordinate properties to the exact projection and projection parameters that were used for that data.

·      Did you try to import a list of addresses and failed? A database that has no location information other than addresses is not geocoded. To be a geocoded database, it must have a latitude and longitude field for each record that shows exactly where that address is located. Databases that do not have a latitude and longitude field for each record must first be geocoded so these field values are computed for each record.

·      Did you expect to get a map and instead got a drawing full of points? Geocoded databases should be tables full of records that include latitude and longitude fields for each record. Importing such a geocoded database will create a drawing that contains points only. Each point is the location of one record.

·      Did you try to import a geocoded database that you thought represented lines and areas coded as a series of records and failed? There is no GIS standard for representing lines or regions in the form of geocoded databases. You may have run across some data that purports to show map features in the form of ASCII lists of records or some other tabular format; however, if it is not one of the standard formats it cannot be read by Manifold. Use one of the formats supported by Manifold to import drawings that contain objects other than points.

 

Imported Tables have wrong field types or missing fields

 

·        Different database formats save data using different approaches to field types. Some primitive format such as .txt or .csv don't save field type information at all. In such cases the importer must guess what data type should be used for that field. It is possible the importer will guess wrong. For example, it might import what you think is date time information as a text string. Use the Transform toolbar to copy/translate the data into the desired field types.

·        When importing from complex formats such as SDTS a file may be imported as many different drawings. Some of them may have certain data fields while others do not. Look through all of the drawings created when looking for given data attributes. Also, some of the more complex formats (like SDTS) may require checking optional import boxes to map fields between tables and drawings.

 

Exported .mdb databases cannot be read by Access 97

 

·        Microsoft changed the .mdb format when going from Access 97 to Access 2000. The new Access 2000 .mdb format cannot be read by Access 97. Manifold writes the new, Access 2000 .mdb format by default. To maintain compatibility with Access 97 you must explicitly specify Access 97 format when exporting tables to .mdb format.

 

Problems importing or exporting to .dbf format

 

·      Have you made sure your Windows system is current as described in the installation instructions? Manifold uses Windows drivers to read and write .dbf files. If your Windows system has not been correctly updated to incorporate the latest Microsoft bug fixes and other current components you may not have proper Windows functioning in this important area.

·      Some programs (especially those in UNIX) do not write .dbf files that are in accordance with Microsoft standards. The fastest way to resolve most problems is to make sure that all names (including file names, field names and so on) have no more than eight, plain alpha characters. See the Importing Tables topic.

 

Cannot write when exporting

 

·      Are you sure you are writing to a directory for which you have write permissions? Your user account may not be authorized to write into that directory. Try writing to a different location.

·      Are you trying to write onto a CD ROM? CDs are not writable. Try writing to a location on hard disk.

·      Are you trying to overwrite a read-only file? If you copied a file from DVD ROM, in Windows that file will continue to be read-only even though you copied it onto the hard disk. The file had "read only" properties set when it was on DVD and copying a file in Windows copies all of the file's properties as well. You need to right-click on the file in Windows explorer and change the properties to make it writable.

·      If you are trying to write into an external database you may not have correct permissions to write into that database. Check with your database administrator to see if the database is writable or if any special passwords or other access methods are required.

·      Are you trying to write information that is not supported by the format? For example, a field name such as "My really long field name for Site $325" cannot be exported to ESRI .shp format due to the limitations on the number of character names allowed in field names in this format. Manifold's exporters will attempt to auto-truncate such names; however, a really determined user may find it possible to defeat such safety measures.

·      Did you see any error messages during installation of Manifold? Manifold must install the latest versions of various Microsoft facilities for accessing data. These include ADO, Jet, DAO, ODBC and OLE DB files if your system does not currently have these standard Microsoft facilities for data access. If any other application is operating, some of these files may be locked and can not be updated. Make sure no background processes are running and re-install Manifold.

 

 

General inability to import tables

 

·      Did you see any error messages during installation of Manifold? Manifold must install the latest versions of various Microsoft facilities for accessing data. These include ADO, Jet, DAO, ODBC and OLE DB files if your system does not currently have these standard Microsoft facilities for data access. If any other application is operating, some of these files may be locked and can not be updated. Make sure no background processes are running and re-install Manifold.

 

Terrain Windows are Blank

 

·      Manifold requires a functioning OpenGL subsystem to display terrains. If there are no OpenGL capabilities in the system terrain windows will be blank when opened.

 

Miscellaneous

 

·      For normal operation you should have four times the maximum size of the files in use available in free disk space. If you are working with a 100 MB image you should have 300 MB free on disk. The extra space is needed to keep temporary versions of the image to allow Undo or abandoning of edits as well as to provide space for copy and paste operations.

·      See the Memory Requirements topic for additional information on RAM and disk space requirements when working with larger projects.