I have QGIS 3.10.7 and QGIS 2.12.3. I am loading the same ASCII (.asc) file into both versions of QGIS. QGIS 3.10.7 says the values in the ASCII file range from 186.573 - 1458.33. QGIS 2.12.3 says the values range from 267.966 - 1142.93.

ArcMap says the range is 549.979 - 1462.79.

Do different programs interpret ASCII files differently? If I were to use SAGA tools to calculate something like slope/aspect/topographic position index using the different programs, I assume the results would be different in absolute terms, but would they be the same/similar in relative terms?

  • 1
    Have you made sure you use the same CRS in all GIS?
    – Erik
    Commented Jun 26, 2020 at 14:32
  • 1
    How are you checkinc the values?
    – Bera
    Commented Jun 26, 2020 at 15:26
  • 2
    Are you sure that the range you get are from the whole value and not from a subset, check the option on all 3 software
    – J.R
    Commented Jun 26, 2020 at 15:33
  • 1
    Link to test data would leave less space for quessing. Also describe how did you exactly get the values so it would be possible to do the same.
    – user30184
    Commented Jun 26, 2020 at 15:40
  • 1
    Does ArcMap show the min/max of data? Or does if report the highest and lowest value used for stretching the color ramp?
    – user30184
    Commented Jun 26, 2020 at 15:43

1 Answer 1


QGIS is just estimating the statistics from a sample, instead of calculating the actual statistics from all of the values.

In the QGIS layer properties - Symbology - Min / Max Value Settings change the Accuracy setting from Estimate (faster) to Actual (slower).

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  • while the accuracy is set to "estimate'', will it produce different results than the accuracy set to -'Actual', for any raster processing such as zonal statistics?
    – GIStree
    Commented Mar 22 at 5:25
  • 1
    The statistics this q refers to are only used for display. They don't affect processing.
    – user2856
    Commented Mar 23 at 2:37

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