Ubuntu – “FreeType NOTFOUND” error when trying to build Okular from source

I am trying to build Okular from source. I checked out commit 8ab768 from Tue Jul 10 17:45:23 2012 +0100. However, FreeType seems to be missing in some path variable. Here is the output from cmake.

$ cd ~/src/okular/build
$ cmake ../ -DCMAKE_INSTALL_PREFIX=~/okular-install -DCMAKE_BUILD_TYPE="Debug"
-- Found Qt-Version 4.8.1 (using /usr/bin/qmake)
-- Found X11: /usr/lib/x86_64-linux-gnu/libX11.so
-- Found KDE 4.8 include dir: /usr/include
-- Found KDE 4.8 library dir: /usr/lib
-- Found the KDE4 kconfig_compiler preprocessor: /usr/bin/kconfig_compiler
-- Found automoc4: /usr/bin/automoc4
-- WARNING: you are using the obsolete 'PKGCONFIG' macro, use FindPkgConfig
-- Found Freetype: -L/usr/lib/x86_64-linux-gnu -lfreetype -lz

-----------------------------------------------------------------------------
-- The following external packages were located on your system.
-- This installation will have the extra features provided by these packages.
-----------------------------------------------------------------------------
   * QImageBlitz - An image effects library
   * libspectre - A PostScript rendering library
   * CHM - A library for dealing with Microsoft ITSS/CHM format files
   * DjVuLibre - A library for dealing with DjVu formatted files
   * libTIFF - A library for reading and writing TIFF formatted files,
   * FreeType - A font rendering engine
   * JPEG - A library for reading and writing JPEG image files.
   * ZLib - The Zlib compression library
   * libepub - A library for reading EPub documents
   * QCA - Qt Cryptographic Architecture (QCA)

-----------------------------------------------------------------------------
-- The following OPTIONAL packages could NOT be located on your system.
-- Consider installing them to enable more features from this software.
-----------------------------------------------------------------------------
   * Poppler-Qt4 (0.12.1 or higher)  <http://poppler.freedesktop.org>
     A PDF rendering library
     Support for PDF files in okular.

-----------------------------------------------------------------------------

CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
FREETYPE_INCLUDE_DIR (ADVANCED)
   used as include directory in directory /home/john/src/okular/generators/dvi

-- Configuring incomplete, errors occurred!

I already tried to set the environment variable as follows.

$ export FREETYPE_INCLUDE_DIR=/usr/include/freetype2/freetype

However, it seems to have no effect. I am using Ubuntu 12.04.

The repository for Okular is available via Git under git://anongit.kde.org/okular.