We shall see in the next section that this uncertainty is propagated to an analogous uncertainty of the stereoscopic reconstruction.

Results
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We present the different perspectives of plumes for two data sets derived from stereoscopic reconstructions in Section \[sec:stereoscopic\_res\], as well as the plume orientation analyses, plume width calculations and the relationship between plumes and EUV bright points. In Section \[sec:stereosc\_SUMER\] the results obtained by combining stereoscopic reconstructions and the plume density and temperature deduced from SUMER observations are shown. The density scale height and its corresponding temperature are calculated by assuming the plume in our study is in hydrostatic equilibrium.

Stereoscopic results {#sec:stereoscopic_res}
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### Side view and top view

In Figure \[fig:side\_view\], we present a view of the 3D placement and direction of polar plumes from a perspective that is $90^{\circ}$ to the left and $20^{\circ}$ up compared to the view direction of *STEREO A*. Of the five reconstructed plumes in April, three are in front of the solar limb as seen from *STEREO A*, the other two are behind the limb. For the data set in June, only plume 6 lies in front of solar limbs as seen by both spacecraft. The black solid lines indicate 