I have a 4 band GeoTiff file that represents the degree of vegetation in an area, with a cell size of 30x30. I want to convert it to a shapefile so I can add it to another shapefile (so I can run an OLS).
But I don't know how to convert to tif to a shp. I have tried reading forums online but I keep coming unstuck. Any help or advice would be appreciated.
That will never convert to a shapefile because of the complexity of the image. It needs to be far more generalized and cleaned up. Every speckle on the image that is slightly different from its neighbor will attempt to become a polygon. That image need further reclassification to reduce the number of areas to a manageable size.
Both might get you more responses. Also tagging Managing Data
I agree with Dan that simplifying might be in order, but converting to a file GDB polygon layer before a shape file. It might offer more flexibility and options. Once you have it ready, then export to a shape. Shapes may have other restrictions.
As to converting, How Polygon To Raster works—Help | ArcGIS Desktop might be a good starting point.