topic Re: High-resolution aerial imagery not displaying properly in Mapping Questions

High-resolution aerial imagery not displaying properly

BrandonGuiher — Wed, 01 Jul 2015 14:34:13 GMT

ArcGIS 10.0 Desktop

Windows 7 64bit

We received county-wide aerial imagery in .ECW format. Uncompressed file size is approximately 45 GB. The imagery will load, but with an error (re: missing spatial data), and at extremely low resolution (very blurry). Not sure if the problems are related or not. The image does appear to load in the proper location and alignment, but the real issue is the display resolution. Thanks ahead of time for any assistance!

Re: High-resolution aerial imagery not displaying properly

JayantaPoddar — Wed, 01 Jul 2015 14:41:57 GMT

Brandon,

The imageries are missing spatial reference. You need to georeference the data. What is the source of the data?

Re: High-resolution aerial imagery not displaying properly

BrandonGuiher — Wed, 01 Jul 2015 14:47:04 GMT

Jayanta,

Data was provided by the County from a flown aerial survey.

Re: High-resolution aerial imagery not displaying properly

DanPatterson_Retired — Wed, 01 Jul 2015 14:52:43 GMT

My first inclination was to suggest building pyramids and statistics but according to Build Pyramids And Statistics—Help | ArcGIS for Desktop Wavelet compressed raster datasets, such as ECW and MrSID, do not need to have pyramids built. These formats have internal pyramids that are created upon encoding.

There are problems with ArcMap 10.3 .ecw rasters not correctly projecting in ArcGIS Desktop 10.3 which was attributed to a spatial reference issue. So I would check your image properties to see whether they make any sense, then try to assign it the appropriate coordinate system since the pyramids are already handled but I don't know about the statistics given the size of your image.

Re: High-resolution aerial imagery not displaying properly

LisaTurner — Wed, 01 Jul 2015 15:03:59 GMT

Hey Brandon,

I don't know if this will be the same for you or not, but when I worked with my first .ECW style orthos I had to make sure I had an up to date NCSEcw.dll file, and I haven't had an issue since. It could be worth checking. The Arc help menu suggested renaming the file's extension, and then going to the control panel and running the change/ repair option.

Re: High-resolution aerial imagery not displaying properly

BrandonGuiher — Wed, 01 Jul 2015 15:06:45 GMT

Thanks Dan. I went to ArcToolBox>Data Management Tools>Projections>Raster>Define Projection. It looks like the file has State Plane coordinates, so I defined State Plane, Pennsylvania South, and am currently awaiting the results. Another issue I am having is the size of the file itself; once it is loaded, if I do anything with it, I get major lag / unresponsive program. Is there a way to break the file into smaller, more manageable pieces?