Raster File Format Recommendations

[BrianHaren]

I'm curious (not concerned, just curious) about raster performance issues in ArcPad running on a Trimble Juno 3D.

My team needs to tile out a high resolution aerial of a large airport for field data collection purposes.

In their videos the ArcPad development team seems to prefer the TIFF format.  My experience, however, is that TIFF files tend to be significantly larger than JPEG or JPEG2000. 

So far we've tested JPEG and JPEG2000 file formats.  JPEG seems to hold a slight performance edge over JPEG2000, but since ArcPad doesn't seem to be able to read the JPEG world file we get an error message every time a JPEG file is opened telling us that there's not spatial reference assigned to the image and asks if we'd like to assume the file is in our chosen coordinate system (State Plane).  For the experienced user this is not an issue, but these Junos are going into the hands of non-GIS types and if I don't have to deal with regular questions about 'error messages' I'd rather not.

So just out of curiosity, is there a compelling reason to pick TIFF over JPEG or JPEG2000 for projects like mine?  Even though TIFF files are much larger (for the same given area of coverage and pixel resolution), does ArcPad handle them more efficiently than JPEG?

As we say here in the colonies, inquiring minds want to know!

Brian

[GarethWalters · Accepted solution]

Hi Brian,

The reason why we suggest TIFF is that is not compressed and therefore makes it faster to read through strips of data.  It is a constent battle to decide what is best as people want the best imagery possible, at the smallest size, on limited hardware. Unfortunately there is going to trade off somewhere. Check out these blog posts and perhaps that might give a better idea of what you require.

http://arcpadteam.blogspot.com.au/2006/08/raster-tips-1-choosing-raster-format.html
http://arcpadteam.blogspot.com.au/2008/04/raster-tips-2.html

Now on the error message. Perhaps if you don't have one already, create a .prj for the TIFF. That should fix the problem.

From one curious mind to the other, let us know how you go :confused:

Cheers,
Gareth

[BrianHaren]

Gareth,

Thanks for the info.  I generated several image tiles of the same area in a number of raster formats and found out, as you discuss, that TIFF performs best.  The experience is a little counter-intuitive since we've always used compressed raster formats in ArcGIS Desktop to save file space and improve performance.

The file sizes of the TIFFs, while a bit worrisome at first, really are not an issue.  SD cards are so cheap now that I can load up one with all our raster data and still have plenty of space left over for vector data.

Thanks for your help!

Brian

[ColinMurray]

I've found that large extent (5x5km) coloured tiffs can really take time to load and have opted to use greyscale to reduce file size and hence improve loading speed. I also find colour imagery tends to interfere with vector layers and is difficult to see in bright light conditions.

I'd like to know of an easy way to convert colour imagery to greyscale in ArcGIS. From what I read on the forums it's not an easy process.

[AllisonFerrini]

I've found that large extent (5x5km) coloured tiffs can really take time to load and have opted to use greyscale to reduce file size and hence improve loading speed. I also find colour imagery tends to interfere with vector layers and is difficult to see in bright light conditions.

I'd like to know of an easy way to convert colour imagery to greyscale in ArcGIS. From what I read on the forums it's not an easy process.

The way I do this when exporting a TIFF file (arc 10.1) is:
1. Zoom to the extent you want the file to be.
2. Click File, Export Map
3. Save as type: TIFF
4. On the Options Tab, there are two tabs: General and Format.
-General tab is where you select resolution, width, height, and whether or not to write a World File for georeferencing.
-Format tab is where you select Color, Compression, Background color, and whether or not to write GeoTIFF tags.
Color options are 24 bit True Color, 8 bit Palette, 8 bit greyscale, 1 bit monochrome mask, and 1 bit monochrome threshold.
5. Save as greyscale!
6. Done.

[PaulLohr]

I have been using ECW format imagery with the ECW extension for a while in ArcPad. This has worked very well, even on 16-bit devices with ECW files nearing 2 GB.

The old version 6 extension may work on the newest version of ArcPad. It was working with a beta 10 version of ArcPad.

I do have a Windows 8 device with the newest version of ArcPad and can't get the ECW extension to install (even with the special instructions from arcpadteam.blogspot.com.au).