From 9c190d74bb720911c7e46721316ea06ffdaaf0a5 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Mon, 7 Sep 2020 21:46:13 +1000
Subject: [PATCH] Fix #981. Incorrect and inaccurate conversion to imperial
 units in quantities.

---
 src/ifcblenderexport/blenderbim/bim/helper.py     | 4 ++--
 src/ifcblenderexport/blenderbim/bim/operator.py   | 2 +-
 src/ifcopenshell-python/ifcopenshell/util/unit.py | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/ifcblenderexport/blenderbim/bim/helper.py b/src/ifcblenderexport/blenderbim/bim/helper.py
index a58f66c019..38d29b5bcb 100644
--- a/src/ifcblenderexport/blenderbim/bim/helper.py
+++ b/src/ifcblenderexport/blenderbim/bim/helper.py
@@ -18,12 +18,12 @@ class SIUnitHelper:
         'yard': 0.914,
         'mile': 1609,
         'square inch': 0.0006452,
-        'square foot': 0.09290,
+        'square foot': 0.09290304,
         'square yard': 0.83612736,
         'acre': 4046.86,
         'square mile': 2588881,
         'cubic inch': 0.00001639,
-        'cubic foot': 0.02832,
+        'cubic foot': 0.02831684671168849,
         'cubic yard': 0.7636,
         'litre': 0.001,
         'fluid ounce UK': 0.0000284130625,
diff --git a/src/ifcblenderexport/blenderbim/bim/operator.py b/src/ifcblenderexport/blenderbim/bim/operator.py
index 5d58561dbb..8ec739e300 100644
--- a/src/ifcblenderexport/blenderbim/bim/operator.py
+++ b/src/ifcblenderexport/blenderbim/bim/operator.py
@@ -3464,7 +3464,7 @@ class GuessQuantity(bpy.types.Operator):
     def get_prefix_name(self, value):
         if '/' in value:
             return value.split('/')
-        return None, bpy.context.scene.BIMProperties.area_unit
+        return None, value
 
     def get_blender_prefix_name(self):
         if bpy.context.scene.unit_settings.system == 'IMPERIAL':
diff --git a/src/ifcopenshell-python/ifcopenshell/util/unit.py b/src/ifcopenshell-python/ifcopenshell/util/unit.py
index a001b085d5..20a29ca4ac 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/unit.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/unit.py
@@ -17,12 +17,12 @@ si_conversions = {
     'yard': 0.914,
     'mile': 1609,
     'square inch': 0.0006452,
-    'square foot': 0.09290,
+    'square foot': 0.09290304,
     'square yard': 0.83612736,
     'acre': 4046.86,
     'square mile': 2588881,
     'cubic inch': 0.00001639,
-    'cubic foot': 0.02832,
+    'cubic foot': 0.02831684671168849,
     'cubic yard': 0.7636,
     'litre': 0.001,
     'fluid ounce UK': 0.0000284130625,