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I'm changing raster layers in ArcMap from WGS84 to BTM (Bangladesh Transverse Mercator). I first set my data frame to be in BTM

[BTM Projection: Transverse_Mercator False_Easting: 500000.0 False_Northing: -2000000000.0 Central_Meridian: 90.0 Scale_Factor: 0.9996 Latitude_Of_Origin: 0.0 Linear Unit: Meter (1.0)]

When I add the layers I'm asked to do a datum transformation apparently. I found two transformation datum which differ in ΔZ. Which one is accurate?

First one: ΔX -283.729m ΔY -735.942m ΔZ -261.143m

Second: ΔX -283.729m ΔY -735.942m ΔZ -161.143m

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  • The BTM seems to be a custom one, did you used the project tool to convert from WGS to BTM?
    – Yogesh Chavan
    Dec 21, 2020 at 15:32
  • yes it's a custom one, and yes I used the project raster tool but that's a later step, this transformation window appeared to me once I entered the layers since they are in WGS84. Then I did the transformation using the X,Y,Z above. Then I used project raster tool to convert them from WGS84 to BTM.
    – Areej
    Dec 21, 2020 at 16:25

2 Answers 2

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When I've processed data in Bangladesh and it has been supplied to me in BTM (Bangladesh Transverse Mercator) it sometimes comes with the datum set to GCS_Everest_Bangladesh. I have found if I set the datum to be GCS_Gulshan_303 I generally get better alignment.

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    Yes I agree, even I had a few projects involving India-Bangladesh borders, there the data used to be in the UTM zone(45 & 46) with their datum in WGS 84, for BTM the datum was Everest Bangladesh, and for Gulshan 303 it was the same datum Gulshan 303 with spheroid Everest Bangladesh Adjustment 1937
    – Yogesh Chavan
    Dec 21, 2020 at 19:09
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[BTM Projection: Transverse_Mercator False_Easting: 500000.0 False_Northing: -2000000.0 Central_Meridian: 90.0 Scale_Factor: 0.9996 Latitude_Of_Origin: 0.0 Linear Unit: Meter (1.0)]

First one: ΔX -283.729m ΔY -735.942m ΔZ -261.143m is a correct.

The above information is correct.

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