Everyday utilities from the IndiGEO data room - the same calculations we run when georeferencing legacy maps and preparing datasets for capture. Free to use, no sign-up.
Enter a location to identify its Survey of India sheet - the 1:1M, 1:250k and 1:50k numbers used on legacy Indian toposheets.
Numbering per the India & Adjacent Countries series as used on legacy SOI toposheets. Coverage: approx. 68°-100°E, 4°-40°N. Verify sheet-edge coordinates against an SOI index map.
Convert between geographic (lat/long) and UTM grid coordinates on WGS84.
WGS84 ellipsoid. At map-digitising accuracy WGS84 UTM is interchangeable with MGA (GDA94/GDA2020) in Australia - EPSG codes shown for both. Differences are sub-metre; use a projection library for survey-grade work.
Enter a location to identify the national 1:250,000 sheet code and 1:100,000 sheet number.
Codes per the Australian national topographic map series (e.g. SH51-09, 3136). Sheet names are not included - cross-check codes on the Geoscience Australia index.
Working out how to scan a paper map? Convert between scan DPI and ground resolution at a given map scale.
Rule of thumb: 300 DPI suits most legacy toposheets; use 400-600 DPI for dense linework, faint contours or small text. Scanning finer than the drawing accuracy of the original adds file size, not information.
These tools locate and prepare your maps - our team turns them into structured, SME-verified, GIS-ready datasets.