# Tckmap error! how to change the tck header

**URL:** <https://community.mrtrix.org/t/tckmap-error-how-to-change-the-tck-header/1523>\
**Category:** Uncategorized\
**Created:** [March 13, 2018, 1:38pm UTC](https://community.mrtrix.org/t/tckmap-error-how-to-change-the-tck-header/1523 "2018-03-13T13:38:30Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![rsmith](https://community.mrtrix.org/user_avatar/community.mrtrix.org/rsmith/32/2672_2.png) [@rsmith](https://community.mrtrix.org/u/rsmith)\
**Post date:** [March 13, 2018, 11:28pm UTC](https://community.mrtrix.org/t/tckmap-error-how-to-change-the-tck-header/1523/2 "2018-03-13T23:28:38Z")

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Hi Ting,

It’s not surprising that these data won’t contain step size information, since they will have been converted from whatever format they were produced in into `.tck` using some external conversion software.

My response in a similar recent thread [here](https://community.mrtrix.org/t/error-tckmap-cannot-perform-streamline-mapping-no-step-size-information-in-track-file-header/1514/2) likely provides the solution: Manually provide the `-upsample` option to `tckgen`, so that it no longer depends on this track header information.

Cheers  
Rob

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