MidTex DLG Reader

Create custom basemaps from DLG's


MidTex DLG Reader DESCRIPTION
Picture

DLG Reader Introduction
DLG Reader Product Capabilities
Using the DLG Reader
Begin the Import with the DLG Reader
Using the Import Dialog Box in the DLG Reader
Select Directory for Input in the DLG Reader
DLG Reader File List Box
Setting the Projection Parameters
The Finished Product
Import GNIS Labels into the DLG Reader
DLG Reader Requirements

Introduction to the DLG Reader

If you use AutoCAD for mapping purposes, what you have probably been doing is purchasing basemap information in DWG or DXF format and importing it over your other mapping information. Basemap information from custom data providers can be good, but expensive. When the data is available on the USGS Internet FTP server free of charge, why not use a less expensive method for putting basemaps together?

The MidTex DLG Reader for AutoCAD will be of great benefit to companies that need accurate digital information but don't want to pay the high prices that basemap providers charge. It is seamlessly integrated as a native ARX extension to the AutoCAD desktop. You can use the same exact data that companies like American Digital Cartography (ADC) use without having to pay exorbitant rates. Considering that charges are $100 for half of a 1:100K digital quad, this program can pay for itself immediately.

DLG Reader Product Capabilities

Using the DLG Reader

The following is a description of the steps for creating custom basemaps using the MidTex DLG Reader.
Picture

Begin the Import with the DLG Reader

Issue the command "dlgin" at the AutoCAD Command prompt. The software will take advantage of the AutoCAD demandload feature, whereby an application can "load itself" into memory when called upon to perform an action. This feature allows the AutoCAD user to have only the programs in memory necessary for the operations being performed during the session.

Using the Import Dialog Box in the DLG Reader

The dialog box that appears after the "dlgin" command is issued allows you to choose which DLGs you want to load from a list of all DLGs in the directory. This is helpful since one "map" may consist of several layers of information. Note that additional information is displayed for each layer. All DLGs in the selected directory are automatically marked for import; deselect the files you do not want with CTRL+left click. As you select different directories in the directory box, the dialog will display available files in the list box on the right. If you would like AutoCAD to automatically zoom to the area where the DLGs are being imported, you can select the "Zoom to Import Extents" check box.

Select Directory for Input in the DLG Reader

This is a typical directory list box that allows you to navigate any of the drives and directories that are currently available to the local system. This includes all "special" drives as well, for example, CD-ROMs, Jazz drives, network drives, etc.

DLG Reader File List Box

This list box allows you to select/deselect specific files in the currently selected directory. Extra information is displayed so that you can more easily decide which files you need. Note that the USGS map name, layer name, and scale are included in this information.

Setting the Projection Parameters with the DLG Reader

The parameter box allows you to set the input map projection parameters (see figure below).
Picture

This screen lets you set the Earth Model, Coordinate System, Units, and Zone. If you do not check the Perform Transformation check box, the DLG will be pulled in with its default coordinate system (UTM, NAD27, meters). The zone will be displayed in the Set Import Parameters dialog box.

The Finished Product

Once you click on "OK" to the Set Import Parameters dialog box, the DLG Reader will begin the import process. You should then be able to view your map.
Picture

Partial display of sample DLGs included with the software. (GNIS labels are included in this graphic. See below for instructions on importing GNIS data with DLG data.)

Importing GNIS Labels with the DLG Reader

GNIS files are USGS-maintained databases that hold information about place names on the map. Importing GNIS files into the AutoCAD drawing is simple: