## 5 Conclusions  
This study has presented a new algorithm to obtain and match keypoints in low-variance images like DEMs. Our results have demonstrated the feasibility of matching DEMs with different resolutions, different variances, and a large set of keypoints. This will allow us to apply different quality control assessments to large samples. Moreover, the large sets of matched keypoints can determine the changing zones by displacement. In addition, the zones with missing keypoints could define great changes between the DEMs. Both types of information can be used for multitemporal studies. The algorithm has been tested using large sets of data (DEMs), with differences in variance, resolutions, slopes, and other height descriptors, which has confirmed the viability of the proposed methodology. Moreover, all the used data are publicly available and can be checked by any other researcher. Our future work will focus on improving the initial alignment using other keypoints with enrichment descriptors of pixels surpassing the proposed local maxima and minima and checking the different approaches for testing, like multirings and other zone matching descriptors that will be defined using simulations based on known deformations to test the accuracy of these changes. Conceptualization, M.A.U.-C. and A.T.M.-C.; methodology, M.A.U.-C. and A.T.M.-C.; software, M.A.U.-C.; validation, M.A.U.-C.; formal analysis, M.A.U.-C.; investigation, M.A.U.-C. and A.T.M.-C.; resources, M.A.U.-C. and A.T.M.-C.; data curation, M.A.U.-C.; writing--original draft preparation, M.A.U.-C. and A.T.M.-C.; writing--review and editing, M.A.U.-C. and A.T.M.-C.; visualization, M.A.U.-C. and A.T.M.-C.; supervision, M.A.U.-C. and A.T.M.-C.; project administration, M.A.U.-C. and A.T.M.-C.; funding acquisition, M.A.U.-C. and A.T.M.-C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. * [PERSON] and [PERSON] (2006) [PERSON]; [PERSON] Causes and consequences of error in digital elevation models. _Prog. Phys. Geogr._**2006**, _30_, 467-489. [CrossRef]
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