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    <p>With building:part you are actually describing 3D volumes. These
      volumes don't necessarily start at ground level, but ideally
      should not intersect in 3D. As you can see in the Simple 3D
      building specification, you can set a "building:min_level" and
      "min_height" to "raise" a certain part from ground level to its
      appropriate starting height. So in your case of a large single
      story ground level part, and a smaller top section, you could set
      building:min_level and min_height tags on the part for the smaller
      section to raise it above the large section/part, which in that
      case should NOT  be a multipolygon.</p>
    <p>Of course, like you suggested, there is the alternative solution
      of creating a multipolygon and setting the higher part to start at
      ground level as well by not specifying building:min_level and
      min_height, and that would be correct too in terms of
      non-intersecting 3D volumes, but the first solution without
      multipolygon seems more logical in this case (unless the higher
      part was in reality a true separate section starting at a ground
      level, e.g. office, within a larger structure, in which case it
      might make sense to use the MP option if you would like to tag
      function on the building:part as well).</p>
    <p>Marco<br>
    </p>
     <br>
    <div class="moz-cite-prefix">Op 18-8-2017 om 10:36 schreef Javier
      Sánchez Portero:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAFZgtEh46zwTSP=aKGfZryXyyG+CRWGtbqDvSUHgvZxOXAq3mw@mail.gmail.com">
      <div dir="ltr">Sorry, I should have taken time to give some
        examples. Please read below (I rev.<br>
        <div class="gmail_extra"><br>
          <div class="gmail_quote">2017-08-18 1:30 GMT+01:00 Clifford
            Snow <span dir="ltr"><<a
                href="mailto:clifford@snowandsnow.us" target="_blank"
                moz-do-not-send="true">clifford@snowandsnow.us</a>></span>:<br>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
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              <div dir="ltr"><br>
                <div class="gmail_extra"><br>
                  <div class="gmail_quote"><span class="gmail-">On Thu,
                      Aug 17, 2017 at 4:12 PM, Javier Sánchez Portero <span
                        dir="ltr"><<a
                          href="mailto:javiersanp@gmail.com"
                          target="_blank" moz-do-not-send="true">javiersanp@gmail.com</a>></span>
                      wrote:<br>
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                          <div><br>
                            I am thinking in ways to reduce the
                            complexity that introduces the mapping of
                            parts of buildings. For example:<br>
                          </div>
                        </div>
                      </blockquote>
                    </span></div>
                </div>
              </div>
            </blockquote>
            <div><br>
              I have reversed the order of the points <br>
              <br>
            </div>
            <div>
              <blockquote class="gmail_quote" style="margin:0px 0px 0px
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                <div dir="ltr">
                  <div class="gmail_extra">
                    <div class="gmail_quote"><span class="gmail-">
                        <blockquote class="gmail_quote"
                          style="margin:0px 0px 0px
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                          <div dir="ltr">
                            <div>* In the wiki [1] says that the outline
                              should be tagged with building:levels and
                              height, but this, if the parts cover the
                              whole outline, is a duplication since
                              these tags will always be in some of the
                              parts. Could I delete the part(s) whose
                              labels match those of the outline?<br>
                            </div>
                          </div>
                        </blockquote>
                        <div><br>
                        </div>
                      </span>
                      <div>If you use a multipolygon, then the
                        multipolygon would contain the levels and
                        height.  </div>
                    </div>
                  </div>
                </div>
              </blockquote>
              <div><br>
                I'm refering to 3D modeling of building height and
                levels, according to [1]. For example, this building [2]
                have two heights and should be drawn two parts inside
                the building footprint, one with (building:part=yes,
                building:levels=1, height=3) [3], and another one with
                (building:part=yes, building:levels=2, height=6). As the
                building footprint [2] could have the levels and height
                tags I put them in it avoiding to draw one part. I
                meant, the building area is not entirely covered by
                building:part areas. All the building in this village
                was drawn according to this.<br>
                <br>
                I take the rule to put in the building:levels and height
                tags of the full building those of the level wich parts
                sum a greatest area instead of the maximum values. For a
                example see the adjacent building to the left [4]. It
                have (building:levels=1, height=3) instead of the
                maximum values (building:levels=2, height=6) of the
                building:part [5]. This way I avoid to draw two parts
                inside the building. I consider that the maximum
                building:levels and height could be calculated by a
                consumer from the building and its parts instead. I'm
                wrong with it? But it's against what says the wiki [6].<br>
              </div>
               </div>
            <blockquote class="gmail_quote" style="margin:0px 0px 0px
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              <div dir="ltr">
                <div class="gmail_extra">
                  <div class="gmail_quote"><span class="gmail-">
                      <blockquote class="gmail_quote" style="margin:0px
                        0px 0px 0.8ex;border-left:1px solid
                        rgb(204,204,204);padding-left:1ex">
                        <div dir="ltr">
                          <div>* If one part is inscribed within a
                            larger one, can I use simple ways overlapped
                            and leave to the render decide how to draw
                            them or should I create a multipolygon for
                            the larger part with the smaller part with
                            inner role? I'm prone to the first.<br>
                          </div>
                        </div>
                      </blockquote>
                      <div><br>
                      </div>
                    </span>
                    <div>An example would help. If the building has an
                      inner court yard, then a multipolygon would be
                      appropriate, with the inner court yard with an
                      inner role. <br>
                    </div>
                  </div>
                </div>
              </div>
            </blockquote>
            <div><br>
            </div>
            <div>I'm not referring to buildings with holes but to nested
              building:part areas. Consider this building [7] with a big
              one-story part and a smaller two-story part [8] within it.
              If I use the full detailled schema I will need a
              multipolygon relation for the one-story part, but I avoid
              this putting the tags in the footprint (violating the rule
              of maximum levels and height in it). I don't have real
              example at hand, but supposes another three-story part
              inscribed inside the two-story part [8]. should I use a
              multipolygon for the two-story part to fully separate it
              area from the three-story part area? Or could I just draw
              the inner three-story part, overlapping both areas?<br>
              <br>
              [1] <a
                href="https://wiki.openstreetmap.org/wiki/Simple_3D_buildings"
                moz-do-not-send="true">https://wiki.openstreetmap.org/wiki/Simple_3D_buildings</a><br>
              [2] <a href="http://www.openstreetmap.org/way/459549932"
                moz-do-not-send="true">http://www.openstreetmap.org/way/459549932</a><br>
              [3] <a href="http://www.openstreetmap.org/way/459550128"
                moz-do-not-send="true">http://www.openstreetmap.org/way/459550128</a><br>
              [4] <a href="http://www.openstreetmap.org/way/459549958"
                moz-do-not-send="true">http://www.openstreetmap.org/way/459549958</a><br>
              [5] <a href="http://www.openstreetmap.org/way/459550129"
                moz-do-not-send="true">http://www.openstreetmap.org/way/459550129</a><br>
              [6] <a
                href="https://wiki.openstreetmap.org/wiki/Key:building:part"
                moz-do-not-send="true">https://wiki.openstreetmap.org/wiki/Key:building:part</a><br>
              [7] <a href="http://www.openstreetmap.org/way/215569626"
                moz-do-not-send="true">http://www.openstreetmap.org/way/215569626</a><br>
              [8] <a href="http://www.openstreetmap.org/way/459573978"
                moz-do-not-send="true">http://www.openstreetmap.org/way/459573978</a><br>
            </div>
          </div>
          <br>
        </div>
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      <br>
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      <br>
      <pre wrap="">_______________________________________________
Tagging mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Tagging@openstreetmap.org">Tagging@openstreetmap.org</a>
<a class="moz-txt-link-freetext" href="https://lists.openstreetmap.org/listinfo/tagging">https://lists.openstreetmap.org/listinfo/tagging</a>
</pre>
    </blockquote>
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