2

I am completing a remote sensing paper and am doing most of the work in PCI Geomatica, where I have 2 separate files. One from running a texture analysis algorithm containing 6 band layers from a satellite image. The other set from running an unsupervised classification on the same image with the original 6 band layers, as well as the texture analysis bands amalgamated to aid the classification, classification results which are two bands (input, output channels) giving me a total of 16 band layers. The classification itself is aggregated into 3 classes. My desire is to compare the correlation between the results of the classification (3 classes) against the results of the texture analysis quantitatively.

I am aware the GIS does not like pix files. I am considering converting both to TIFF files. My query is do I need to take any additional steps to run zonal statistics on these two image files correctly?

  • 1
    GeoTiff is just fine. What version of ArcGis are you using? the reason I ask is from v10 ArcGis uses GDAL for some raster functions so it can open BigTiff where v9.X and before will not open very large Tiff files. It would be a good idea to look at the properties of the rasters in ArcCatalog to ensure the NoData value (if present), georeference and spatial reference has been written in a format that Esri can understand - a big problem when going between platforms. Is ERDAS Imagine (.img) format an option? I often find this is the most 'honest' interchange format. – Michael Stimson Jul 1 '15 at 21:23
  • Hey Michael, thanks for the quick reply. I believe it would be 10.22 as my university updates whenever there is a new release.I will confirm this tomorrow and report back as I shall be attempting to do this in the lab. – Chris Medyna Jul 1 '15 at 21:28
2

The GeoTiff format is a good format for interchange with ArcGis, it is one of few that:

  • Supports more than 3 bands.
  • Has a wide range of pixel types (from 1 bit to 32bit signed/unsigned/float).
  • Has multiple compression options (from none to JPEG/Lossy).

Read more about supported raster formats from the Esri docs.

It is a good idea to verify the spatial reference, geolocation and NoData value of the converted images to ensure the conversion software has written these tags in a format that Esri (using GDAL) understands. Right click on the raster in ArcCatalog, go to properties and check/set the values for the raster.

GeoTiff files can have many tags in their header, most of which are not GIS related; because the format has been developing for a long time under different strains tags written by some software does not get recognized by other software... because of this (and other reasons) I often find that the ERDAS Imagine Image format (.img) is the best interchange format to pass between software packages, it was entirely developed by ERDAS so there should be no difference between an ENVI img, Esri img, ERDAS img, GDAL img... however img only supports RLE compression, which is mostly worse than no compression.

Prior to ArcGis v10 Esri did not support BigTiff (larger than 4GB) format, be aware of that if you are still using ArcGis 9.X. The ERDAS img file though an img/ige format can be recognized by ArcGis 9.X with sizes larger than 4GB, which would make that about the only option for passing large files between packages without altering the cell values with lossy compression (jp2, ecw).

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.