本人准备的ceres包版本为1.12.0（可在ceres-solver\include\ceres\version.h中看到），Ubuntu18.10，安装的eigen版本为3.3.9，在ceres的make阶段，出现如下图的错误：
可能的问题就是eigen3.3版本与ceres有冲突，这里我选择了更换eigen的版本为3.2.5，下载地址为： https://bitbucket.org/eigen/eigen/get/3.2.5.tar.bz2
因为之前已经安装的3.3.9版本，因此，再安装另一个版本的eigen时候要选择其它目录，我选择了安装在 根目录下：
1、进入根目录，打开终端运行 sudo mkdir eigen3,，注意这里的文件夹名称最好为eigen3
2、进入eigen安装包，运行:
mkdir build;
cmake .. -D -CMAKE_INSTALL_PREFIX=/eigen3 -EIGEN_INCLUDE_INSTALL_DIR=/eigen3 ;
sudo make install
即可将该版本eigen安装在根目录下，如果不指定安装目录和头文件目录的话，会默认安装在 /usr/local中，这会和之前安装的高版本eigen冲突。
3、接下来开始安装ceres，在这之前要先编辑一下 /ceres-solver/cmake/FindEigen.cmake文件，这里将内容全部列出来，可直接粘贴覆盖掉原cmake文件中的内容即可：
# Ceres Solver - A fast non-linear least squares minimizer
# Copyright 2015 Google Inc. All rights reserved.
# http://ceres-solver.org/
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * Neither the name of Google Inc. nor the names of its contributors may be
# used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# Author: [email protected] (Alex Stewart)
#
# FindEigen.cmake - Find Eigen library, version >= 3.
#
# This module defines the following variables:
#
# EIGEN_FOUND: TRUE iff Eigen is found.
# EIGEN_INCLUDE_DIRS: Include directories for Eigen.
#
# EIGEN_VERSION: Extracted from Eigen/src/Core/util/Macros.h
# EIGEN_WORLD_VERSION: Equal to 3 if EIGEN_VERSION = 3.2.0
# EIGEN_MAJOR_VERSION: Equal to 2 if EIGEN_VERSION = 3.2.0
# EIGEN_MINOR_VERSION: Equal to 0 if EIGEN_VERSION = 3.2.0
#
# The following variables control the behaviour of this module:
#
# EIGEN_INCLUDE_DIR_HINTS: List of additional directories in which to
# search for eigen includes, e.g: /timbuktu/eigen3.
#
# The following variables are also defined by this module, but in line with
# CMake recommended FindPackage() module style should NOT be referenced directly
# by callers (use the plural variables detailed above instead). These variables
# do however affect the behaviour of the module via FIND_[PATH/LIBRARY]() which
# are NOT re-called (i.e. search for library is not repeated) if these variables
# are set with valid values _in the CMake cache_. This means that if these
# variables are set directly in the cache, either by the user in the CMake GUI,
# or by the user passing -DVAR=VALUE directives to CMake when called (which
# explicitly defines a cache variable), then they will be used verbatim,
# bypassing the HINTS variables and other hard-coded search locations.
#
# EIGEN_INCLUDE_DIR: Include directory for CXSparse, not including the
# include directory of any dependencies.
# Called if we failed to find Eigen or any of it's required dependencies,
# unsets all public (designed to be used externally) variables and reports
# error message at priority depending upon [REQUIRED/QUIET/<NONE>] argument.
macro(EIGEN_REPORT_NOT_FOUND REASON_MSG)
unset(EIGEN_FOUND)
unset(EIGEN_INCLUDE_DIRS)
# Make results of search visible in the CMake GUI if Eigen has not
# been found so that user does not have to toggle to advanced view.
mark_as_advanced(CLEAR EIGEN_INCLUDE_DIR)
# Note <package>_FIND_[REQUIRED/QUIETLY] variables defined by FindPackage()
# use the camelcase library name, not uppercase.
if (Eigen_FIND_QUIETLY)
message(STATUS "Failed to find Eigen - " ${REASON_MSG} ${ARGN})
elseif (Eigen_FIND_REQUIRED)
message(FATAL_ERROR "Failed to find Eigen - " ${REASON_MSG} ${ARGN})
else()
# Neither QUIETLY nor REQUIRED, use no priority which emits a message
# but continues configuration and allows generation.
message("-- Failed to find Eigen - " ${REASON_MSG} ${ARGN})
endif ()
return()
endmacro(EIGEN_REPORT_NOT_FOUND)
# Search user-installed locations first, so that we prefer user installs
# to system installs where both exist.
#
# TODO: Add standard Windows search locations for Eigen.
list(APPEND EIGEN_CHECK_INCLUDE_DIRS
/eigen3)
# Additional suffixes to try appending to each search path.
list(APPEND EIGEN_CHECK_PATH_SUFFIXES
eigen3 # Default root directory for Eigen.
Eigen/include/eigen3 ) # Windows (for C:/Program Files prefix).
# Search supplied hint directories first if supplied.
# Mark internally as found, then verify. EIGEN_REPORT_NOT_FOUND() unsets
# if called.
set(EIGEN_FOUND TRUE)
set(EIGEN_INCLUDE_DIR,/eigen3)
# This is on a single line s/t CMake does not interpret it as a list of
# elements and insert ';' separators which would result in 3.;2.;0 nonsense.
set(EIGEN_VERSION "3.2.5")
# Set standard CMake FindPackage variables if found.
if (EIGEN_FOUND)
set(EIGEN_INCLUDE_DIRS /eigen3)
endif (EIGEN_FOUND)
# Handle REQUIRED / QUIET optional arguments and version.
include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(Eigen
REQUIRED_VARS EIGEN_INCLUDE_DIRS
VERSION_VAR EIGEN_VERSION)
# Only mark internal variables as advanced if we found Eigen, otherwise
# leave it visible in the standard GUI for the user to set manually.
if (EIGEN_FOUND)
mark_as_advanced(FORCE EIGEN_INCLUDE_DIR)
endif (EIGEN_FOUND)4、运行cmake .. ; make; sudo make install ; 即可顺利完成安装，可以看到这里ceres默认安装位置依然是/usr.local。
5、个人感觉比较坑的地方就是之前安装的Sophus需要的eigen需要是3.3版本，这样必须装两个版本的eigen才行，不知道有没有一个兼容的解决方法。