## 4 Conclusions  
The use of high-resolution satellite imagery and digital elevation models (DEM) for the extraction of morphometric parameters of different positive and negative landforms is extremely useful especially over large and remote areas where detailed topographic maps are not available. The Pleiades satellite constellation delivers images with a ground resolution of 0.5 m, and their use in a GIS environment allows to automatically extract very precise planimetric measurements. We used Pleiades images to extract morphometric measurements of the doline fields opening in the basaltic plateau of Azrou, in the Middle Atlas (Morocco). To verify the accuracy of the vertical measurements calculated from the  
Figure 10: Examples of typical dolines that produced the highest depth differences. (**A**) mixed geometry doline with dense vegetation and boulders; (**B**) funnel-shaped deep doline with blocks and boulders on the bottom; (**C**) funnel-shaped doline with high trees covering the bottom; (**D**) shallow flat-shaped doline with dry stone walls at the bottom and near the knickpoints. Figure 9: (**A**) Scatterplot of the depth (D) measures calculated in the field and in the DEM for the entire population (N = 89). (**B**) Scatterplot of the subset without outliers (N = 84). Lines represent the best-fit of the linear regression model. Pleiades-derived DEM, we carried out a ground-truthing on a subset of 89 different dolines (out of a total of 357 identified using low-resolution satellite data including LANDSAT 7 ETM+, ASTER, and ESA Sentinel 2). We found an overall good correlation (\(p\)-value \(<\) 0.05 and correlation coefficient >0.9) between the DEM-derived depths and those measured with telemeter in the field. The largest differences were obtained on deep funnel-shaped dolines and on shallow bowl-shaped dolines, where disturbance is created by tall trees, human-built structures (dry walls), boulders, or a combination of these features. Our study shows that very-high-resolution satellite images such as Pleiades (0.5 m ground resolution), are extremely useful in obtaining precise planimetric measurements on large landforms such as dolines. DEMs extracted from Pleiades stereo images deliver good results on the vertical scale if doline floors are not masked by vegetation or disturbed by large debris (boulders or dry walls), with mean depth errors of 2 \(\pm\) 2 m.  
These results will allow for extending the information extracted in the field to the dolines present in inaccessible areas of the plateau, allowing to obtain more information to complete their morphological profiling and propose a model on their unknown origin. The results of our work demonstrate that tri-stereo satellite images are suitable for the morphometric assessment of shadow-prone negative and positive landforms, and might also be used for the analysis of skylights and collapses on lava flows on the Moon and on Mars, where vegetation or human-built structures are completely lacking, as preparatory surveys for future robotic and human explorations of extraterrestrial caves [31; 32; 33]. [PERSON], [PERSON] and [PERSON] wrote the original draft and performed the editing of the manuscript. [PERSON] performed the DEM extraction and the morphometric measurements; [PERSON] and [PERSON] performed the fieldwork in 2016; [PERSON] performed the statistical analyses and DEM validation. All authors have read and agreed to the published version of the manuscript. Pleiades images were granted in 2018 in the framework of the project entitled \"The Azrou Plateau (Middle Atlas, Morocco): a perfect terrestrial analogue for studying both karst and lava tube collapses with remote sensing techniques\" (RITM0042620--ESA-TPM4 Project Proposal id43487, PI MTM). Fieldwork was carried out in Autumn 2016 in the project \"The Azrou Plateau (Middle Atlas, Morocco): a perfect terrestrial analogue for studying both karst and lava tube collapses with remote sensing techniques and field geology, Europlanet project 16-EPN2-007 (PI JDW). Not applicable.