Overlay two images from different sources

[badar]

Hi all,

    When we overlay different images from different sources, there might be the problem of difference in resolution. Consider a scenario where we want to calculate landuse per defined elevation zones. Say, we classify landuse from LandSat Imagery and use SRTM DEM for the delineation of elevation zones. Both have spatial resolution of 30 m and 90 m respectively. OK. Now we resample our DEM to 30 m from 90 m. Use a shapefile or some aoi layer to subset both images for our AOI.

    If we now zoom in to the pixel level, we'll come to know that pixels of both images aren't aligned despite being at the same resolution now. This can be more problematic when dealing with high but different resolutions of two datasets where we want to calculate landuse area per defined zones. Scenario can be different but we face problems like that when doing some work on RS.

  I've two questions in this regard

1. What if we apply some zonal tool to calculate area without tackling misalignment of pixels and one pixel of landuse lies in 2 or more zones equally. In which zone this particular pixel will be counted?

2. How to tackle misalignment of pixels?

Thanks in Advance for your time.

Regards

[pasfans01]

for tackling the misalignment problem, if you use ILWIS, you can use glue maps tool to align and refer a raster into another raster, but yes, the process will make another resampling process, and you know consequences of more resampling

[badar]

pasfand01. So what do you suggest me to do. Carry on with the misaligned pixels or resample/align pixels and then start working? I mean to say, I am going to calculate area per defined zone but pixels of both layers are not aligned. Which way inherent less error?