DDR files as used with Log ASCII Standard (LAS) format used for well logging data. This is a legacy format different from the LAS format used for LiDAR data. LAS is a format originally developed by the Canadian Well Logging society in the late 1980's.
DDR files are most often encountered with older raster data from archival sites providing satellite images recorded by earth observation satellites in the 1990's. Typical data comes from Advanced Very High Resolution Radiometer (AVHRR) devices. The AVHRR is a broadband, four or five channel (depending on the model) scanner, sensing in the visible, near-infrared, and thermal infrared bands.
Remarkably, for such an old format, DDR LAS files will usually provide projection information so that the images created from them will have the correct projection assigned on import.
There are frequently two files in a LAS data set using DDR files, a .ddr file and a .img file. The illustration above shows data sets for two bands, channel 1 and channel 5 of an AVHRR instrument. To import, we would choose the .ddr file.
To import from DDR, LAS format:
Choose File-Import from the main menu.
In the Import dialog browse to the folder containing data of interest.
Double-click the file ending in .ddr for the data of interest.
A table and an image will be created.
Clicking on the p13ch1.ddr file for the file folder shown above will result in the creation of a table and an image that displays the data in the table.
We can double-click the image to view it. For a more interesting display, we first create a new data source using a Bing street maps image server as shown in the Example: An Imageserver Tutorial topic. We then create a map and drag and drop the Bing layer into the map, and then we drag and drop the p13ch1 image into the map.
The image appears using the correct projection. In the illustration above we have also added above the image a Google streets layer with transparency to provide reference labels. The image seen above is the same map published in larger size and also in a zoomed in view on the Data Sources page on the Manifold website.
Zooming in we see it is a satellite image of the US. This is just one channel of the five channel data acquired by the AVHRR instrument.
We can import the p13ch5.ddr files as well to create another image that shows the channel 5 data.
DDR LAS files are rarely met in modern times but can be useful for research investigating long term changes in land coverage when using archived satellite imagery. Most often they are used to create false color RGB images by combining bands, using methods similar to those shown in the Example: Import BIL and Combine 3 Bands topic.
Example: Spectacular Images and Data from Web Servers
Example: An Imageserver Tutorial
Example: Import BIL and Combine 3 Bands