Question: how to do ndwi in erdas imagine?
Answer: Formula for NDWI. NIR - SWIR. ...  For Landsat. Band4 – Band5. ...  Make a New Model for NDWI as. Give the Input of Band 4 and Band 5. Apply the Tool Function as per Formula. Give the Output file with Float Single Option. Execute the Model and Check its Execution Status. Load your NDWI Image in ERDAS Window for further Parameters Study.