界画是中国传统绘画中一奇特的画种，它在中国古代亭台楼阁的建筑不断完美中应运而生，在中国绘画史的记载中，界画就是绘制古代建筑特殊的画种。界画与其他画种相比有一个明显的特征，就是要求画家对古代建筑有足够的知识与了解，凭借一支界笔及界尺准确的描绘，工整、细致、一丝不苟，素有“尺寸层叠皆以准绳为则，殆犹修内司法式，分秒不得逾越之”评介。

　　界画的起源早在晋代就有记载，顾恺之《论画》有“台榭一定器耳，难成而易好，不待迁想妙得也”。界画除却自身绘画的不凡价值外，它还起到了对中国古代建筑记录、传承的重要作用。古代建筑多是以土木结构构架而成，由于用材的原因，大多古建在历史的变迁、兵火战乱中毁于一旦，现存者所剩无几。所以界画的这一绘画形势对于认识和研究古代建筑就显得尤为重要。

　　作为绘制在纸、绢上的界画我们已无法看到，但在敦煌壁画和唐代墓葬的壁画中亦有所存，如唐代德懿太子李重润墓道西壁《阙楼图》，既是早期的大型界画。更值得重笔一提的是在山西境内繁峙县岩山寺内尚存有金代弥足珍贵，四壁辉煌的界画壁画。其艺术水准之高，堪称我国古代绘画史上的上乘之作。到此不免要一提担忧之念，因为此山地处偏远，鉴于种种因由庙宇年久失修，此绝响之作正在随着岁月风雨的侵蚀以及人为的伤害日渐破损。借此文一呼：护我国宝！

　　在中国绘画史上由于界画的制作难学、难工、难做，并未形成于世广传的画种，更在清代界画大家袁江、袁耀父子界画大家之后几乎无人在钟情于斯。现在的画家千千万，但研究和制作界画者则寥若晨星，十分罕见了！继1979年去世的江西画家黄秋园先生留下几幅界画作品之后，界画已成了濒临灭绝的画种。然而，现在我们高兴地看到，当代著名旅美画家冯长江先生向我们展示了他先后用了三年的时间创作了五幅当代人眼中的界画。冯先生凭着对艺术的执着，也凭着他在任山西省壁画研究院副院长之际，积累的对古建筑的知识和临摹古代壁画的经验，以超人的毅力和劳动，再现了这一古代绝响的画种，使面临灭绝的中国传统优秀绘画画种重现于世。这里，我们将这五幅界画作品编印于本辑。此举正如冯先生所说：“我并不期望通过自己的努力或抛砖引玉，使这一画种得以复苏，它的确太费心、费时、费力，在当今急功近利的浮躁的艺术界很难为人瞩目而效之，但要世人不要忘却，中国还有这样精深的优秀的传统绘画艺术，在继黄秋园先生之后还有画家愿为此一为”。

　　Ruler painting is a special kind of traditional Chinese painting that appeared along with the development of the ancient pavilions, terraces and towers. As recorded, it is painting on ancient buildings. Compared with other kinds of paintings, it has an obvious feature that required the painter to have enough knowledge about and understanding of ancient buildings so that he could carefully and meticulously finish the work with his brush and ruler. So, it was said that ruler paintings were made by strictly following the standards and rules without any violation.

　　There was record about the origination of ruler paintings in the Jin Dynasty. Gu Kaizhi said in his On Painting, "Both pavilions and terraces have certain shapes. Therefore, although it is difficult to paint about them, good effect can be shown even without imagination."With extraordinary value, ruler paintings play an important role in the recording and inheritance of the ancient buildings of China. Most of the ancient buildings were soil and wood structures so that many were destroyed during the historical development, especially during wars. Therefore, there are only a few of them left. So, ruler paintings are of great significance for understanding and studying on ancient buildings.

　　We now have no chance to see the ruler paintings on paper and silk. However, we can see those among the murals in Dunhuang and the tombs of Tang Dynasty. For example, there is The Side Tower, which was found on the west wall of the tomb of Li Chongrun, Prince Deyi of Tang Dynasty. It is one of the earliest large ruler paintings. In addition, there is the splendid ruler painting wall of the Jin Dynasty in the Yanshan Temple in Fanshi County, Shanxi. Boasting high art level, it is one of the most marvelous works in the history of ancient paintings of China. However, since it is located in remote mountainous area and is not maintained well for a variety of reasons, it's being increasingly damaged by the wind and rain and human activities. We should protect the treasure of our country!

　　Ruler painting is difficult to learn and make so that it was not widely spread. What's more, there were few people engaged in ruler painting after Yuan Jiang and his son Yuan Yao, who were both famous painters in the Qing Dynasty. There are many contemporary painters, but few of them are engaged in study and creation of ruler paintings. Ruler paintings are going extinct after 1979, when Huang Qiuyuan (a painter born in Jiangxi, China) made several ruler paintings. However, it is pleased to see that there are still some painters devoting themselves to ruler painting. For example, Feng Changjiang, a Chinese painter living in the United States, took three years to make five ruler paintings. With persistence in art and as the vice president of Shanxi Institute of Mural, Feng has accumulated rich knowledge about ancient buildings and experience in imitating ancient murals. With great efforts, he devotes himself to inheriting the ruler painting skills and making the excellent traditional Chinese paintings widely known by the modern people. Therefore, we made the album of the five works by Feng to make ruler paintings widely known. Feng said, "I do not expect to lead to the revitalization of ruler painting, which takes too much time and efforts to learn and make so that it is hard for it to catch too much attention of the art circle that now seeks quick success and instant benefits. I just expect that people will not forget that there is so excellent traditional art in China and there are painters who would like to do something for it following Mr. Huang Qiuyuan. "